---
title: Identify the principal reason for which flaps and slats are deployed… — Why planes fly · tree and pragmatics
description: Identify the principal reason for which flaps and slats are deployed prior to landing. Exam question 2 of lesson 22 «Why planes fly» of the technology 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 · Why planes fly

<!-- .ven lang=en -->
Identify the principal reason for which flaps and slats are deployed prior to landing.

<!-- .vintro -->
**Mova's choice:** option 1 · **The right answer:** option 3 · wrong ✗ · **Who acts:** you · **What happens:** identify, deploy · **To what, where:** principal reason, flaps

<!-- .vabout -->
This is exam question 2 of lesson 22 «Why planes fly» of the technology 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/technology/22-why-planes-fly/#e2).

## The question {#question}

```conllu
# sent_id = question:technology:22-why-planes-fly:e2:1
# text = Identify the principal reason for which flaps and slats are deployed prior to landing.
1	Identify	identify	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	4	det	_	_
3	principal	principal	ADJ	JJ	Degree=Pos	4	amod	_	_
4	reason	reason	NOUN	NN	Number=Sing	1	obj	_	_
5	for	for	ADP	IN	_	6	case	_	_
6	which	which	PRON	WDT	PronType=Rel	11	obl	_	_
7	flaps	flap	NOUN	NNS	Number=Plur	11	nsubj:pass	_	_
8	and	and	CCONJ	CC	_	9	cc	_	_
9	slats	slat	NOUN	NNS	Number=Plur	7	conj	_	_
10	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	11	aux:pass	_	_
11	deployed	deploy	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	4	acl:relcl	_	_
12	prior	prior	ADJ	JJ	Degree=Pos|ExtPos=ADP	14	case	_	_
13	to	to	ADP	IN	_	12	fixed	_	_
14	landing	landing	NOUN	NN	Number=Sing	11	obl	_	SpaceAfter=No
15	.	.	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 reason |  |  |  |  | vn characterize-29.2-1-1 «NP V NP S\_ING»: agent=Agent reason=Theme |
| 2 | **deploy** | present · passive |  | flaps and slats |  |  |  | for the principal reason; prior landing | tree rules |

<!-- .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 -->
They serve to collect precipitation and increase the mass of the aircraft

```conllu
# sent_id = question:technology:22-why-planes-fly:e2:o1:1
# text = They serve to collect precipitation and increase the mass of the aircraft
1	They	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	2	nsubj	_	_
2	serve	serve	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	to	to	PART	TO	_	4	mark	_	_
4	collect	collect	VERB	VB	VerbForm=Inf	2	advcl	_	_
5	precipitation	precipitation	NOUN	NN	Number=Sing	4	obj	_	_
6	and	and	CCONJ	CC	_	7	cc	_	_
7	increase	increase	VERB	VB	VerbForm=Inf	4	conj	_	_
8	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
9	mass	mass	NOUN	NN	Number=Sing	7	obj	_	_
10	of	of	ADP	IN	_	12	case	_	_
11	the	the	DET	DT	Definite=Def|PronType=Art	12	det	_	_
12	aircraft	aircraft	NOUN	NN	Number=Sing	9	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **serve** | present | They |  |  |  |  |  | vn masquerade-29.6-2 «NP V PP.attribute»: agent=Agent |
| 2 | **collect** | to-infinitive | They *not said here* | precipitation |  |  |  |  | vn obtain-13.5.2 «NP V NP»: agent=Agent precipitation=Theme |
| 3 | **increase** | infinitive | They *not said here* | the mass of the aircraft |  |  |  |  | vn caused\_calibratable\_cos-45.6.2-1 «NP V NP.patient»: agent=Causer mass=Patient |

### Option 2 {#o2}

<!-- .ven lang=en -->
They are deployed solely in order to increase velocity

```conllu
# sent_id = question:technology:22-why-planes-fly:e2:o2:1
# text = They are deployed solely in order to increase velocity
1	They	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	3	nsubj:pass	_	_
2	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	aux:pass	_	_
3	deployed	deploy	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
4	solely	solely	ADV	RB	_	3	advmod	_	_
5	in	in	ADP	IN	_	6	case	_	_
6	order	order	NOUN	NN	Number=Sing	3	obl	_	_
7	to	to	PART	TO	_	8	mark	_	_
8	increase	increase	VERB	VB	VerbForm=Inf	3	advcl	_	_
9	velocity	velocity	NOUN	NN	Number=Sing	8	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **deploy** | present · passive |  | They |  | order |  | solely *property* | tree rules |
| 2 | **increase** | to-infinitive |  | velocity |  |  |  |  | vn caused\_calibratable\_cos-45.6.2-1 «NP V NP.patient»: agent=Causer velocity=Patient |

### Option 3 · ✓ the right answer {#o3}

<!-- .ven lang=en -->
They enlarge and curve the wing, permitting flight at a reduced speed

```conllu
# sent_id = question:technology:22-why-planes-fly:e2:o3:1
# text = They enlarge and curve the wing, permitting flight at a reduced speed
1	They	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	2	nsubj	_	_
2	enlarge	enlarge	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	and	and	CCONJ	CC	_	4	cc	_	_
4	curve	curve	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	2	conj	_	_
5	the	the	DET	DT	Definite=Def|PronType=Art	6	det	_	_
6	wing	wing	NOUN	NN	Number=Sing	4	obj	_	SpaceAfter=No
7	,	,	PUNCT	,	_	8	punct	_	_
8	permitting	permit	VERB	VBG	Tense=Pres|VerbForm=Part	4	advcl	_	_
9	flight	flight	NOUN	NN	Number=Sing	8	obj	_	_
10	at	at	ADP	IN	_	13	case	_	_
11	a	a	DET	DT	Definite=Ind|PronType=Art	13	det	_	_
12	reduced	reduce	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	13	amod	_	_
13	speed	speed	NOUN	NN	Number=Sing	8	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **enlarge** | present | They |  |  |  |  |  | vn other\_cos-45.4 «NP.patient V»: agent=Patient |
| 2 | **curve** | present | They *not said here* | the wing |  |  |  |  | vn knead-26.5 «NP V NP.material»: agent=Agent wing=Material |
| 3 | **permit** | gerund | They *not said here* | flight |  | a reduced speed |  |  | vn admit-64.3-1 «NP V NP PP.location»: agent=Agent flight=Theme at speed=Location |
| 4 | **reduce** | participle |  |  |  |  |  |  | vn limit-76 «NP V NP»: agent=Causer |

### Option 4 {#o4}

<!-- .ven lang=en -->
They are intended to abrade the runway and arrest the aircraft

```conllu
# sent_id = question:technology:22-why-planes-fly:e2:o4:1
# text = They are intended to abrade the runway and arrest the aircraft
1	They	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	3	nsubj:pass	_	_
2	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	aux:pass	_	_
3	intended	intend	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
4	to	to	PART	TO	_	5	mark	_	_
5	abrade	abrade	VERB	VB	VerbForm=Inf	3	xcomp	_	_
6	the	the	DET	DT	Definite=Def|PronType=Art	7	det	_	_
7	runway	runway	NOUN	NN	Number=Sing	5	obj	_	_
8	and	and	CCONJ	CC	_	9	cc	_	_
9	arrest	arrest	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	conj	_	_
10	the	the	DET	DT	Definite=Def|PronType=Art	11	det	_	_
11	aircraft	aircraft	NOUN	NN	Number=Sing	9	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **intend** | present · passive |  | They |  |  |  |  | tree rules |
| 2 | **abrade** *not said to happen* | to-infinitive |  | the runway |  |  |  |  | vn other\_cos-45.4 «NP V NP.patient»: agent=Agent runway=Patient |
| 3 | **arrest** | present |  | the aircraft |  |  |  |  | vn prosecute-33.2-1 «NP V NP»: agent=Agent aircraft=Patient |

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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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