---
title: Identify the principal reason for which the lunar sky appears black… — Thinking like an astronomer · tree and pragmatics
description: Identify the principal reason for which the lunar sky appears black even during the lunar day. Exam question 3 of lesson 10 «Thinking like an astronomer» 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 3 · Thinking like an astronomer

<!-- .ven lang=en -->
Identify the principal reason for which the lunar sky appears black even during the lunar day.

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

<!-- .vabout -->
This is exam question 3 of lesson 10 «Thinking like an astronomer» 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/10-reasoning-about-space/#e3).

## The question {#question}

```conllu
# sent_id = question:world:10-reasoning-about-space:e3:1
# text = Identify the principal reason for which the lunar sky appears black even during the lunar day.
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	10	obl	_	_
7	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
8	lunar	lunar	ADJ	JJ	Degree=Pos	9	amod	_	_
9	sky	sky	NOUN	NN	Number=Sing	10	nsubj	_	_
10	appears	appear	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	acl	_	_
11	black	black	ADJ	JJ	Degree=Pos	10	xcomp	_	_
12	even	even	ADV	RB	_	16	advmod	_	_
13	during	during	ADP	IN	_	16	case	_	_
14	the	the	DET	DT	Definite=Def|PronType=Art	16	det	_	_
15	lunar	lunar	ADJ	JJ	Degree=Pos	16	amod	_	_
16	day	day	NOUN	NN	Number=Sing	10	obl:unmarked	_	SpaceAfter=No
17	.	.	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 | **appear** | present | the lunar sky |  |  |  | day | for the principal reason; black *property* | vn appear-48.1.1 «NP V»: agent=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 -->
The lunar dust absorbs the whole of the light that falls upon it

```conllu
# sent_id = question:world:10-reasoning-about-space:e3:o1:1
# text = The lunar dust absorbs the whole of the light that falls upon it
1	The	the	DET	DT	Definite=Def|PronType=Art	3	det	_	_
2	lunar	lunar	ADJ	JJ	Degree=Pos	3	amod	_	_
3	dust	dust	NOUN	NN	Number=Sing	4	nsubj	_	_
4	absorbs	absorb	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
5	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
6	whole	whole	ADJ	JJ	Degree=Pos	9	amod	_	_
7	of	of	ADP	IN	_	9	case	_	_
8	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
9	light	light	NOUN	NN	Number=Sing	4	obj	_	_
10	that	that	PRON	WDT	PronType=Rel	11	nsubj	_	_
11	falls	fall	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	9	acl:relcl	_	_
12	upon	upon	ADP	IN	_	13	case	_	_
13	it	it	PRON	PRP	Case=Acc|Gender=Neut|Number=Sing|Person=3|PronType=Prs	11	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **absorb** | present | the lunar dust | the whole light |  |  |  |  | vn absorb-39.8 «NP V NP»: agent=Goal light=Theme |
| 2 | **fall** | present | the whole light |  |  | dust |  |  | vn occur-48.3 «NP V PP»: agent=Theme upon it=Location |

### Option 2 {#o2}

<!-- .ven lang=en -->
The Earth obstructs the sunlight before it reaches the Moon

```conllu
# sent_id = question:world:10-reasoning-about-space:e3:o2:1
# text = The Earth obstructs the sunlight before it reaches the Moon
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	Earth	Earth	PROPN	NNP	Number=Sing	3	nsubj	_	_
3	obstructs	obstruct	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
5	sunlight	sunlight	NOUN	NN	Number=Sing	3	obj	_	_
6	before	before	SCONJ	IN	_	8	mark	_	_
7	it	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	8	nsubj	_	_
8	reaches	reach	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	advcl	_	_
9	the	the	DET	DT	Definite=Def|PronType=Art	10	det	_	_
10	Moon	Moon	PROPN	NNP	Number=Sing	8	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **obstruct** | present | the Earth | the sunlight |  |  |  |  | vn discourage-64.5-1 «NP V NP»: agent=Causer sunlight=Eventuality |
| 2 | **reach** | present | Earth | the Moon |  |  |  |  | vn body\_motion-49.2-1-1 «NP V NP ADV»: agent=Agent moon=Theme |

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

<!-- .ven lang=en -->
The Moon possesses no atmosphere to scatter sunlight

```conllu
# sent_id = question:world:10-reasoning-about-space:e3:o3:1
# text = The Moon possesses no atmosphere to scatter sunlight
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	Moon	Moon	PROPN	NNP	Number=Sing	3	nsubj	_	_
3	possesses	possess	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	no	no	DET	DT	PronType=Neg	5	det	_	_
5	atmosphere	atmosphere	NOUN	NN	Number=Sing	3	obj	_	_
6	to	to	PART	TO	_	7	mark	_	_
7	scatter	scatter	VERB	VB	VerbForm=Inf	3	advcl	_	_
8	sunlight	sunlight	NOUN	NN	Number=Sing	7	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **possess** | present | the Moon | no atmosphere |  |  |  |  | vn own-100.1 «NP V NP»: agent=Pivot atmosphere=Theme |
| 2 | **scatter** | to-infinitive | the Moon *not said here* | sunlight |  |  |  |  | vn spray-9.7-1 «NP V NP.theme»: agent=Agent sunlight=Theme |

### Option 4 {#o4}

<!-- .ven lang=en -->
The Sun does not illuminate the surface of the Moon at all

```conllu
# sent_id = question:world:10-reasoning-about-space:e3:o4:1
# text = The Sun does not illuminate the surface of the Moon at all
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	Sun	Sun	PROPN	NNP	Number=Sing	5	nsubj	_	_
3	does	do	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	5	aux	_	_
4	not	not	PART	RB	Polarity=Neg	5	advmod	_	_
5	illuminate	illuminate	VERB	VB	VerbForm=Inf	0	root	_	_
6	the	the	DET	DT	Definite=Def|PronType=Art	7	det	_	_
7	surface	surface	NOUN	NN	Number=Sing	5	obj	_	_
8	of	of	ADP	IN	_	10	case	_	_
9	the	the	DET	DT	Definite=Def|PronType=Art	10	det	_	_
10	Moon	Moon	PROPN	NNP	Number=Sing	7	nmod	_	_
11	at	at	ADP	IN	_	12	case	_	_
12	all	all	DET	DT	PronType=Tot	5	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **not** **illuminate** | present · do-support | the Sun | the surface of the Moon |  | all |  |  | vn illustrate-25.3 «NP V NP»: agent=Agent surface=Destination |

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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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