---
title: Identify the principal constituent gas of the atmosphere. — Air and why we need it · tree and pragmatics
description: Identify the principal constituent gas of the atmosphere. Exam question 2 of lesson 17 «Air and why we need it» of the world course of Mova's primary school, with the dependency tree and pragmatics of the question and of each option; Mova's choice was wrong.
---

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# Exam question 2 · Air and why we need it

<!-- .ven lang=en -->
Identify the principal constituent gas of the atmosphere.

<!-- .vintro -->
**Mova's choice:** option 1 · **The right answer:** option 4 · wrong ✗ · **Who acts:** you · **What happens:** identify · **To what, where:** principal constituent gas

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This is exam question 2 of lesson 17 «Air and why we need it» of the world course of Mova's primary school, asked in stiff, formal language. The page gives the question's syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause, then the 4 options as the student saw them, each with its tree and pragmatics. Every text is parsed by Mova itself. How the student answered it, with the score of every option and why: [the test at school](https://md.mova.elamur.ai/free/en/school-run/world/17-air-oxygen-carbon-dioxide/#e2).

## The question {#question}

```conllu
# sent_id = question:world:17-air-oxygen-carbon-dioxide:e2:1
# text = Identify the principal constituent gas of the atmosphere.
1	Identify	identify	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
3	principal	principal	ADJ	JJ	Degree=Pos	5	amod	_	_
4	constituent	constituent	NOUN	NN	Number=Sing	5	compound	_	_
5	gas	gas	NOUN	NN	Number=Sing	1	obj	_	_
6	of	of	ADP	IN	_	8	case	_	_
7	the	the	DET	DT	Definite=Def|PronType=Art	8	det	_	_
8	atmosphere	atmosphere	NOUN	NN	Number=Sing	5	nmod	_	SpaceAfter=No
9	.	.	PUNCT	.	_	1	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **identify** | imperative | you *not said here* | the principal constituent gas of the atmosphere |  |  |  |  | vn characterize-29.2-1-1 «NP V NP S\_ING»: agent=Agent gas=Theme |

<!-- .note -->
One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

## The options {#options}

### Option 1 · ← Mova's choice {#o1}

<!-- .ven lang=en -->
Oxygen

```conllu
# sent_id = question:world:17-air-oxygen-carbon-dioxide:e2:o1:1
# text = Oxygen
1	Oxygen	oxygen	NOUN	NN	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

### Option 2 {#o2}

<!-- .ven lang=en -->
Water vapour

```conllu
# sent_id = question:world:17-air-oxygen-carbon-dioxide:e2:o2:1
# text = Water vapour
1	Water	water	NOUN	NN	Number=Sing	2	compound	_	_
2	vapour	vapour	NOUN	NN	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

### Option 3 {#o3}

<!-- .ven lang=en -->
Carbon dioxide

```conllu
# sent_id = question:world:17-air-oxygen-carbon-dioxide:e2:o3:1
# text = Carbon dioxide
1	Carbon	carbon	NOUN	NN	Number=Sing	2	compound	_	_
2	dioxide	dioxide	NOUN	NN	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

### Option 4 · ✓ the right answer {#o4}

<!-- .ven lang=en -->
Nitrogen

```conllu
# sent_id = question:world:17-air-oxygen-carbon-dioxide:e2:o4:1
# text = Nitrogen
1	Nitrogen	Nitrogen	PROPN	NNP	Number=Sing	0	root	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

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**Text:** the tests of Mova's primary school, written for Mova (`world/data/school/`), as the course runner gave them to the student. **Trees:** Mova's own parse — the `en` model on the CPU, when the site is built — not checked by a teacher; they may be wrong. **Frames:** Mova's frames reader (`prag`), each text read on its own. Elamur Cosmic License.

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- ← previous: [Air and why we need it, exam 1](https://md.mova.elamur.ai/free/en/corpora/questions/world/17-air-oxygen-carbon-dioxide/e1/)
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