In short

English expresses wonder by reshuffling a sentence: “how beautiful the sky is!”, “what a day that was!”. Arabic does it with two fixed formulas, and the striking thing about them is that both are قِياسِيّ - regular. You do not learn a list of exclamations; you take a root, pour it into ما أَفْعَلَهُ or أَفْعِلْ بِهِ, and the exclamation exists. ما أَجْمَلَ السَّماءَ! and أَجْمِلْ بِالسَّماءِ! both mean “how beautiful the sky is”, and both were built on the spot from جَمُلَ.

The reason this lesson sits at B2 rather than A2 is that the first pattern is invisible without the vowel marks. ما أجمل السماء is three words that can be an exclamation, a question, or a flat denial, depending entirely on the fatḥas and ḍammas you cannot see. This is the clearest case in the whole path of التَّشْكيل carrying the meaning by itself, so read every vowel here as information, not ornament.

The rule

1. Pattern one: ما + أَفْعَلَ + an accusative noun. The core formula is ما أَفْعَلَهُ. Take a three-radical root, cast it in the shape أَفْعَلَ (a past-tense form), and put the thing you are marvelling at straight after it in the accusative:

• ما أَجْمَلَ السَّماءَ! - how beautiful the sky is.
• ما أَسْرَعَ الوَقْتَ! - how quickly time goes.
• ما أَطْيَبَ الطَّعامَ! - how good the food is.
• ما أَشَدَّ الحَرَّ! - how intense the heat is.

Two fatḥas carry the whole construction: one on the last radical of the verb, one on the end of the noun. Lose either and you have written something else.

2. Why the noun is accusative. A compact parse, because it explains the ending rather than just asserting it. Here ما is not the question word and not the negator: it is an indefinite noun meaning roughly “something great”, and it is the مُبْتَدَأ. أَجْمَلَ is a genuine past-tense verb whose subject is a hidden pronoun referring back to ما. السَّماءَ is therefore its مَفْعولٌ بِهِ, and the little verbal sentence is the خَبَر. Literally: “something has made the sky beautiful” - hence the accusative, and hence the past-tense shape for a present-tense meaning.

3. The verb is frozen. أَجْمَلَ in this pattern never agrees with anything and never changes tense. It stays third-person masculine singular past whatever follows it: ما أَجْمَلَ السَّماواتِ!، ما أَكْرَمَ المُعَلِّماتِ!، ما أَذْكاهُنَّ! Never ما أَجْمَلَتْ, never ما أَجْمَلوا. The two exclamation verbs are جامِدان - frozen - in Arabic grammar, and this is one of them.

4. A pronoun object attaches directly. When the thing admired is already known, it becomes an attached accusative pronoun (lesson 29): ما أَجْمَلَها!، ما أَرْوَعَهُ!، ما أَصْعَبَهُمْ! The pronoun must be the attached object form; a free pronoun after the verb is not Arabic.

5. The noun must be definite or clearly specified. المُتَعَجَّبُ مِنْهُ - the thing you wonder at - is normally definite (ما أَجْمَلَ السَّماءَ!) or an indefinite carrying its own description (ما أَجْمَلَ سَماءً صافِيَةً!). A bare indefinite on its own - ما أَجْمَلَ سَماءً! - has nothing to be astonished at and does not work. A مُضاف counts as specified: ما أَجْمَلَ سَماءَ الصَّحْراءِ!

6. Pattern two: أَفْعِلْ بِـ. The same root in a different mould: أَفْعِلْ بِهِ. It looks like an imperative and is read like one, but it is not a command - grammarians call it a past-tense verb that came out in the shape of an imperative, and its meaning is exactly that of pattern one.

• أَجْمِلْ بِالسَّماءِ! - how beautiful the sky is.
• أَكْرِمْ بِهِ رَجُلًا! - what a fine man he is.
• أَعْظِمْ بِالصَّبْرِ! - how great patience is.

7. In pattern two the بـ is redundant and the form never inflects. The noun after بـ is مَجْرور in writing but is the logical subject; the بـ is a حَرْفُ جَرٍّ زائِد, added for the shape of the formula and translating nothing. Because the verb only wears an imperative costume, it takes no imperative endings at all: you write أَجْمِلْ بِالسَّماءِ! to a woman, to a crowd, to anyone - never أَجْمِلي بِالسَّماءِ, never أَجْمِلوا. What does vary is the pronoun after بـ, since that is a real object of a real preposition: أَكْرِمْ بِهِ!، أَكْرِمْ بِها!، أَكْرِمْ بِهِمْ! An indefinite accusative may follow as a تَمْييز, naming what the wonder is about: أَكْرِمْ بِهِ رَجُلًا!، أَعْظِمْ بِها فِكْرَةً!

8. The flagship contrast: three readings of the same letters. Unvocalized, ما أكرم الرجل is ambiguous three ways. Vocalized, it is not ambiguous at all:

• ما أَكْرَمَ الرَّجُلَ! - exclamation. Verb + accusative object, closed with ”!”.
• ما أَكْرَمُ الرَّجُلِ؟ - question. ما is the interrogative, أَكْرَمُ is the elative of lesson 28 as a nominative predicate, and الرَّجُلِ is genitive as the second term of an إِضافَة: “what is the most generous thing about the man?”
• ما أَكْرَمَ الرَّجُلُ ضَيْفَهُ. - denial. ما is the past negator of lesson 37, أَكْرَمَ is Form IV “he honoured”, الرَّجُلُ is its nominative subject: “the man did not honour his guest.”

Same consonants; the ending on the noun and the mark at the end of the sentence do all the work. One practical note on that mark: Arabic has no separate exclamation point. The character is the ordinary ASCII ”!” that English uses, sitting at the left-hand end of the line. Since Arabic questions do have their own «؟», the pair ”!” vs «؟» is a real visual cue in print, and often the only one an unvocalized text gives you.

9. The six conditions. Not every verb can enter these patterns. The list is exactly the one that governs the elative in lesson 28, which is the cheapest way to remember it: if a root cannot make أَفْعَل as a comparative, it cannot make an exclamation either. The verb must be

1. ثُلاثِيّ - three radicals, so Forms II-X are out (lessons 46-48);
2. تامّ - a full verb, so كانَ وأَخَواتُها (lesson 43) are out;
3. مُتَصَرِّف - it must conjugate, so the frozen verbs لَيْسَ، عَسى، نِعْمَ، بِئْسَ are out;
4. مَبْنِيٌّ لِلْمَعْلوم - active, so a passive (lesson 52) is out;
5. مُثْبَت - affirmative, so a negated verb is out;
6. قابِلٌ لِلتَّفاوُت - gradable, so ماتَ، فَنِيَ، غَرِقَ, which admit no more and no less, are out.

10. And one more exclusion: the أَفْعَل adjectives. If the verb’s own adjective already has the shape أَفْعَل - the colours and the bodily defects - the slot is taken and the pattern is blocked: حَمِرَ / أَحْمَر، خَضِرَ / أَخْضَر، عَرِجَ / أَعْرَج، عَمِيَ / أَعْمى. So ما أَحْمَرَ الوَرْدَ! is not an intensified red rose; it is a broken sentence.

11. When a condition fails, use a helper verb plus a مَصْدَر. The repair is mechanical and extremely common in real prose. Put a suitable ثُلاثِيّ verb into the pattern - ما أَشَدَّ، ما أَكْثَرَ، ما أَعْظَمَ، ما أَجْمَلَ - and hand it the مَصْدَر (lesson 54) of the blocked verb as its accusative object. The noun you actually care about then follows as a مُضافٌ إِلَيْهِ or an attached pronoun:

• ما أَشَدَّ حُمْرَةَ الوَرْدِ! - how red the roses are (colour, blocked by rule 10).
• ما أَكْثَرَ اسْتِخْدامَهُ! - how much it is used (Form X, blocked by condition 1).
• ما أَعْظَمَ انْتِشارَ الظّاهِرَةِ! - how widespread the phenomenon is.
• ما أَشَدَّ تَأَثُّرَهُ بِالخَبَرِ! - how affected he was by the news.

Pattern two takes the same repair: أَشْدِدْ بِحُمْرَةِ الوَرْدِ! For a passive or a negated verb, the helper takes a مَصْدَرٌ مُؤَوَّل instead: ما أَعْظَمَ ما كُتِبَ!، ما أَقْبَحَ أَلّا يَعْتَذِرَ! That مَصْدَرٌ مُؤَوَّل is also the ordinary way to marvel at an action rather than a thing: ما أَجْمَلَ أَنْ نَلْتَقِيَ بَعْدَ سِنينَ!

12. The سَماعِيّ formulas you will actually meet in print. Beside the two regular patterns there are heard, unanalysable expressions. Two are worth owning:

• يا لَهُ مِنْ + indefinite genitive - “what a …”: يا لَهُ مِنْ يَوْمٍ!، يا لَها مِنْ لَيْلَةٍ!، يا لَهُمْ مِنْ رِجالٍ! The pronoun on لَـ agrees with the noun; مِنْ is fixed in modern use - the older variant يا لَهُ رَجُلًا, with an accusative تَمْييز instead, is rare today.
• يا لَـ + genitive - “how great the …!”: يا لَجَمالِ السَّماءِ!، يا لَلْعَجَبِ!، يا لَرَوْعَةِ المَنْظَرِ! Note the fatḥa on the لام here; a plain call carries no لام at all.

Also fully current in modern writing: ما هٰذا الجَمالُ!، أَيُّ يَوْمٍ كانَ ذٰلِكَ! These are nominal sentences with an exclamation mark, not a special pattern, so no case surprises.

13. Two boundaries. يا here is not the vocative particle of lesson 36 - يا وَلَدُ! calls someone, يا لَهُ مِنْ وَلَدٍ! marvels at him. And how formal all of this sounds, and where a modern newspaper prefers a plain intensifier instead, belongs to the register lessons at the end of the path.

Forms & patterns

The two قِياسِيّ patterns, piece by piece:

One root through both moulds, so you can see they are the same object twice:

Weak and doubled roots behave exactly as lessons 49-51 predict - the shape absorbs them:

The blocked verbs and their repairs:

The heard formulas, with the ending each one demands:

Left out on purpose: the classical licences the old grammarians allow around these patterns - separating the verb from its noun by a ظَرْف, exclaiming at an exclamation, and formulas such as لِلَّهِ دَرُّهُ. They belong to older texts, not to written MSA.

Examples

Common mistakes

• ما أَجْمَلُ السَّماءُ! -> ما أَجْمَلَ السَّماءَ! - both endings are wrong at once. The exclamation is a verb plus its accusative object, so it is fatḥa on the verb and fatḥa on the noun; the ḍammas turn it into a half-built question.
• ما أَجْمَلُ السَّماءِ! -> ما أَجْمَلَ السَّماءَ! - a genitive after أَجْمَلُ is the elative reading of lesson 28, “the most beautiful part of the sky”, which needs «؟» and not ”!”.
• ما أَحْمَرَ الوَرْدَ! -> ما أَشَدَّ حُمْرَةَ الوَرْدِ! - colours and defects already own the shape أَفْعَل as adjectives, so they cannot also use it as an exclamation. Go through a helper verb plus the مَصْدَر.
• ما أَسْتَخْدَمَهُ! -> ما أَكْثَرَ اسْتِخْدامَهُ! - اِسْتَخْدَمَ is Form X, not ثُلاثِيّ. The pattern is built only on bare three-radical verbs, never straight off Form VIII or X.
• ما أَجْمَلَتِ السَّماءُ! -> ما أَجْمَلَ السَّماءَ! - the verb in this pattern is frozen. It never takes a feminine ـتْ, a dual, or a plural ending, and the noun after it is not its subject.
• أَجْمِلي بِالسَّماءِ! -> أَجْمِلْ بِالسَّماءِ! - أَفْعِلْ only looks like an imperative. It addresses nobody, so it takes none of the imperative’s person or gender endings.
• أَجْمِلِ السَّماءَ! -> أَجْمِلْ بِالسَّماءِ! - drop the بـ and you have written a genuine command, “make the sky beautiful”. The redundant preposition is what marks the pattern.
• ما أَجْمَلَ هِيَ! -> ما أَجْمَلَها! - the thing admired is an object, so a pronoun must be the attached accusative form of lesson 29, not a free pronoun.
• ما أَجْمَلَ سَماءً! -> ما أَجْمَلَ السَّماءَ! / ما أَجْمَلَ سَماءً صافِيَةً! - the noun has to be definite or given a description; a bare indefinite gives the wonder nothing to hold onto.
• يا لَهُ يَوْمٍ! -> يا لَهُ مِنْ يَوْمٍ! - the noun after مِنْ is an indefinite genitive. Drop مِنْ and the genitive is stranded: the only variant that goes without it puts the noun in the accusative as a تَمْييز (يا لَهُ يَوْمًا), and modern writing keeps مِنْ.

Tips

• Anchor everything on lesson 28: the exclamation and the elative are the same أَفْعَل shape with the same entry requirements. If you can say هٰذا أَجْمَلُ, you can say ما أَجْمَلَ; if you cannot, reach for the helper verb.
• Memorise three helpers - ما أَشَدَّ، ما أَكْثَرَ، ما أَعْظَمَ - plus ما أَجْمَلَ. With a مَصْدَر after them they cover every verb the direct pattern refuses, which in modern vocabulary is most verbs.
• Say the formula with a deliberate double fatḥa, “-a … -a”, every time you drill it. The rhythm is the rule, and it will stop you writing a ḍamma out of habit.
• Write pattern one; recognise pattern two. أَفْعِلْ بِهِ is alive in print and in speeches but is markedly more literary, and mixing up its redundant بـ is an easy way to write a command by accident.
• In unvocalized text look for the accusative you can actually see. Sound masculine plurals and duals show it in the letters: ما أكرم المعلمين cannot be the denial reading, because ـينَ can only be accusative or genitive, never the nominative a subject would need.
• Do not try to translate ما. It is neither “what” nor “not” here, and hunting for an English word for it will only push you toward the wrong vowels.
• Keep يا لَهُ مِنْ … as a single frozen chunk with three slots (لَهُ / لَها / لَهُمْ). It is the most useful exclamation in this lesson for everyday writing, and it needs no root analysis at all.