---
title: Why do birds fluff out their feathers on a frosty day? — Materials and their properties · tree and pragmatics
description: Why do birds fluff out their feathers on a frosty day? Test 2 · ★★ of lesson 18 «Materials and their properties» 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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# Test 2 · ★★ · Materials and their properties

<!-- .ven lang=en -->
Why do birds fluff out their feathers on a frosty day?

<!-- .vintro -->
**Mova's choice:** option 1 · **The right answer:** option 2 · wrong ✗ · **Who acts:** birds · **What happens:** fluff out · **To what, where:** feathers

<!-- .vabout -->
This is test 2 · ★★ of lesson 18 «Materials and their properties» of the world 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/world/18-materials-and-properties/#t2).

## The question {#question}

```conllu
# sent_id = question:world:18-materials-and-properties:t2:1
# text = Why do birds fluff out their feathers on a frosty day?
1	Why	why	ADV	WRB	PronType=Int	4	advmod	_	_
2	do	do	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	4	aux	_	_
3	birds	bird	NOUN	NNS	Number=Plur	4	nsubj	_	_
4	fluff	fluff	VERB	VB	VerbForm=Inf	0	root	_	_
5	out	out	ADP	RP	_	4	compound:prt	_	_
6	their	their	PRON	PRP$	Case=Gen|Number=Plur|Person=3|Poss=Yes|PronType=Prs	7	nmod:poss	_	_
7	feathers	feather	NOUN	NNS	Number=Plur	4	obj	_	_
8	on	on	ADP	IN	_	11	case	_	_
9	a	a	DET	DT	Definite=Ind|PronType=Art	11	det	_	_
10	frosty	frosty	ADJ	JJ	Degree=Pos	11	amod	_	_
11	day	day	NOUN	NN	Number=Sing	4	obl	_	SpaceAfter=No
12	?	?	PUNCT	.	_	4	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **fluff out** | present · do-support | birds | birds's feathers |  |  | day |  | vn other\_cos-45.4 «NP V NP.patient»: agent=Agent feather=Patient |

<!-- .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 -->
To make their feathers dry faster

```conllu
# sent_id = question:world:18-materials-and-properties:t2:o1:1
# text = To make their feathers dry faster
1	To	to	PART	TO	_	2	mark	_	_
2	make	make	VERB	VB	VerbForm=Inf	5	advcl	_	_
3	their	their	PRON	PRP$	Case=Gen|Number=Plur|Person=3|Poss=Yes|PronType=Prs	4	nmod:poss	_	_
4	feathers	feather	NOUN	NNS	Number=Plur	2	obj	_	_
5	dry	dry	VERB	VBP	Mood=Ind|Number=Sing|Person=1|Tense=Pres|VerbForm=Fin	0	root	_	_
6	faster	fast	ADV	RBR	Degree=Cmp	5	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **make** | to-infinitive |  | their feathers |  |  |  |  | vn build-26.1-1 «NP.asset V NP»: agent=Asset feather=Product |
| 2 | **dry** | present |  |  |  |  |  | fast *property* | vn other\_cos-45.4-1 «NP.patient V»: agent=Patient |

### Option 2 · ✓ the right answer {#o2}

<!-- .ven lang=en -->
To trap more air, which insulates them

```conllu
# sent_id = question:world:18-materials-and-properties:t2:o2:1
# text = To trap more air, which insulates them
1	To	to	PART	TO	_	2	mark	_	_
2	trap	trap	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
3	more	more	ADJ	JJR	Degree=Cmp	4	amod	_	_
4	air	air	NOUN	NN	Number=Sing	2	obj	_	SpaceAfter=No
5	,	,	PUNCT	,	_	7	punct	_	_
6	which	which	PRON	WDT	PronType=Rel	7	nsubj	_	_
7	insulates	insulate	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	acl:relcl	_	_
8	them	they	PRON	PRP	Case=Acc|Number=Plur|Person=3|PronType=Prs	7	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **trap** | to-infinitive |  | more air |  |  |  |  | vn trick-59.2 «NP V NP»: agent=Agent air=Patient |
| 2 | **insulate** | present | more air | them *= they* |  |  |  |  | vn butter-9.9 «NP V NP.destination»: agent=Agent they=Destination |

### Option 3 {#o3}

<!-- .ven lang=en -->
To catch the warm wind

```conllu
# sent_id = question:world:18-materials-and-properties:t2:o3:1
# text = To catch the warm wind
1	To	to	PART	TO	_	2	mark	_	_
2	catch	catch	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
3	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
4	warm	warm	ADJ	JJ	Degree=Pos	5	amod	_	_
5	wind	wind	NOUN	NN	Number=Sing	2	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **catch** | to-infinitive |  | the warm wind |  |  |  |  | vn get-13.5.1 «NP V NP»: agent=Agent wind=Theme |

### Option 4 {#o4}

<!-- .ven lang=en -->
To let the cold air reach right down to their skin

```conllu
# sent_id = question:world:18-materials-and-properties:t2:o4:1
# text = To let the cold air reach right down to their skin
1	To	to	PART	TO	_	2	mark	_	_
2	let	let	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
3	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
4	cold	cold	ADJ	JJ	Degree=Pos	5	amod	_	_
5	air	air	NOUN	NN	Number=Sing	2	obj	_	_
6	reach	reach	VERB	VB	VerbForm=Inf	2	xcomp	_	_
7	right	right	ADV	RB	_	8	advmod	_	_
8	down	down	ADV	RB	_	6	advmod	_	_
9	to	to	ADP	IN	_	11	case	_	_
10	their	their	PRON	PRP$	Case=Gen|Number=Plur|Person=3|Poss=Yes|PronType=Prs	11	nmod:poss	_	_
11	skin	skin	NOUN	NN	Number=Sing	8	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **let** | to-infinitive |  | the cold air |  |  |  |  | tree rules |
| 2 | **reach** | infinitive | the cold air *not said here* |  |  |  |  | down *property* | vn body\_motion-49.2-1-1 «NP V»: agent=Agent |

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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: [Materials and their properties, test 1](https://md.mova.elamur.ai/free/en/corpora/questions/world/18-materials-and-properties/t1/)
- next →: [Materials and their properties, test 3](https://md.mova.elamur.ai/free/en/corpora/questions/world/18-materials-and-properties/t3/)
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