---
title: Why is carbon monoxide called a silent danger? — Smells that warn · tree and pragmatics
description: Why is carbon monoxide called a silent danger? Test 4 · ★ of lesson 13 «Smells that warn» of the everyday 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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# Test 4 · ★ · Smells that warn

<!-- .ven lang=en -->
Why is carbon monoxide called a silent danger?

<!-- .vintro -->
**Mova's choice:** option 3 · **The right answer:** option 1 · wrong ✗ · **Who acts:** carbon monoxide · **What happens:** be, call · **To what, where:** carbon monoxide, silent danger · **Speech:** someone speaks here

<!-- .vabout -->
This is test 4 · ★ of lesson 13 «Smells that warn» of the everyday course of Mova's primary school. 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/everyday/13-smells-that-warn/#t4).

## The question {#question}

```conllu
# sent_id = question:everyday:13-smells-that-warn:t4:1
# text = Why is carbon monoxide called a silent danger?
1	Why	why	ADV	WRB	PronType=Int	4	advmod	_	_
2	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	cop	_	_
3	carbon	carbon	NOUN	NN	Number=Sing	4	compound	_	_
4	monoxide	monoxide	NOUN	NN	Number=Sing	0	root	_	_
5	called	call	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	4	acl	_	_
6	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
7	silent	silent	ADJ	JJ	Degree=Pos	8	amod	_	_
8	danger	danger	NOUN	NN	Number=Sing	5	xcomp	_	SpaceAfter=No
9	?	?	PUNCT	.	_	4	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **is a** | present |  | carbon monoxide |  |  |  |  | tree rules |
| 2 | **call** | participle | carbon monoxide *not said here* | a silent danger |  |  |  |  | vn initiate\_communication-37.4.2-1 «NP V»: agent=Agent |

<!-- .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 · ✓ the right answer {#o1}

<!-- .ven lang=en -->
You cannot see, smell or taste it

```conllu
# sent_id = question:everyday:13-smells-that-warn:t4:o1:1
# text = You cannot see, smell or taste it
1	You	you	PRON	PRP	Case=Nom|Person=2|PronType=Prs	4	nsubj	_	_
2	can	can	AUX	MD	VerbForm=Fin	4	aux	_	SpaceAfter=No
3	not	not	PART	RB	Polarity=Neg	4	advmod	_	_
4	see	see	VERB	VB	VerbForm=Inf	0	root	_	SpaceAfter=No
5	,	,	PUNCT	,	_	6	punct	_	_
6	smell	smell	VERB	VB	VerbForm=Inf	4	conj	_	_
7	or	or	CCONJ	CC	_	8	cc	_	_
8	taste	taste	VERB	VB	VerbForm=Inf	4	conj	_	_
9	it	it	PRON	PRP	Case=Acc|Gender=Neut|Number=Sing|Person=3|PronType=Prs	8	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **not** **see** | can | You |  |  |  |  |  | vn comprehend-87.2-1-1 «NP V»: agent=Experiencer |
| 2 | **smell** | infinitive | You *not said here* |  |  |  |  |  | vn smell\_emission-43.3 «NP V»: agent=Theme |
| 3 | **taste** | infinitive | You *not said here* | it |  |  |  |  | vn seem-109 «NP V ADJ»: agent=Theme it=Attribute |

### Option 2 {#o2}

<!-- .ven lang=en -->
It only appears at night

```conllu
# sent_id = question:everyday:13-smells-that-warn:t4:o2:1
# text = It only appears at night
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	3	nsubj	_	_
2	only	only	ADV	RB	_	3	advmod	_	_
3	appears	appear	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	at	at	ADP	IN	_	5	case	_	_
5	night	night	NOUN	NN	Number=Sing	3	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **appear** | present | It |  |  |  | night |  | vn appear-48.1.1 «NP V»: agent=Theme |

### Option 3 · ← Mova's choice {#o3}

<!-- .ven lang=en -->
It makes no sound when it burns

```conllu
# sent_id = question:everyday:13-smells-that-warn:t4:o3:1
# text = It makes no sound when it burns
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	2	nsubj	_	_
2	makes	make	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	no	no	DET	DT	PronType=Neg	4	det	_	_
4	sound	sound	NOUN	NN	Number=Sing	2	obj	_	_
5	when	when	SCONJ	WRB	_	7	mark	_	_
6	it	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	7	nsubj	_	_
7	burns	burn	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	2	advcl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **make** | present | It | no sound |  |  |  |  | vn build-26.1-1 «NP.material V NP»: agent=Material sound=Product |
| 2 | **burn** | present | sound |  |  |  |  |  | vn light\_emission-43.1 «NP V»: agent=Theme |

### Option 4 {#o4}

<!-- .ven lang=en -->
It is too heavy to move around

```conllu
# sent_id = question:everyday:13-smells-that-warn:t4:o4:1
# text = It is too heavy to move around
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	4	nsubj	_	_
2	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	cop	_	_
3	too	too	ADV	RB	_	4	advmod	_	_
4	heavy	heavy	ADJ	JJ	Degree=Pos	0	root	_	_
5	to	to	PART	TO	_	6	mark	_	_
6	move	move	VERB	VB	VerbForm=Inf	4	xcomp	_	_
7	around	around	ADV	RB	_	6	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **is** | present | It |  |  |  |  | heavy *property* | tree rules |
| 2 | **move around** | to-infinitive |  |  |  |  |  | around *property* | vn roll-51.3.1 «NP.theme V»: agent=Theme |

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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: [Smells that warn, test 3](https://md.mova.elamur.ai/free/en/corpora/questions/everyday/13-smells-that-warn/t3/)
- next →: [Smells that warn, test 5](https://md.mova.elamur.ai/free/en/corpora/questions/everyday/13-smells-that-warn/t5/)
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