---
title: Identify the principal reason for the alternation of day and night. — Day and night, shadows and sundials · tree and pragmatics
description: Identify the principal reason for the alternation of day and night. Exam question 1 of lesson 118 «Day and night, shadows and sundials» 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 1 · Day and night, shadows and sundials

<!-- .ven lang=en -->
Identify the principal reason for the alternation of day and night.

<!-- .vintro -->
**Mova's choice:** option 1 · **The right answer:** option 2 · wrong ✗ · **Who acts:** you, day · **What happens:** identify, alternate · **To what, where:** principal reason

<!-- .vabout -->
This is exam question 1 of lesson 118 «Day and night, shadows and sundials» 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/118-day-night-shadows-sundials/#e1).

## The question {#question}

```conllu
# sent_id = question:world:118-day-night-shadows-sundials:e1:1
# text = Identify the principal reason for the alternation of day and night.
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	_	7	case	_	_
6	the	the	DET	DT	Definite=Def|PronType=Art	7	det	_	_
7	alternation	alternation	NOUN	NN	Number=Sing	4	nmod	_	_
8	of	of	ADP	IN	_	9	case	_	_
9	day	day	NOUN	NN	Number=Sing	7	nmod	_	_
10	and	and	CCONJ	CC	_	11	cc	_	_
11	night	night	NOUN	NN	Number=Sing	7	conj	_	SpaceAfter=No
12	.	.	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 |  |  |  | for the alternation of day and night | vn characterize-29.2-1-1 «NP V NP S\_ING»: agent=Agent reason=Theme |
| 2 | **alternate** |  | day |  |  |  |  |  | nom alternation «act intransitive»: of=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 · ← Mova's choice {#o1}

<!-- .ven lang=en -->
The periodic obscuring of the Sun by the Moon

```conllu
# sent_id = question:world:118-day-night-shadows-sundials:e1:o1:1
# text = The periodic obscuring of the Sun by the Moon
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	periodic	periodic	ADJ	JJ	Degree=Pos	0	root	_	_
3	obscuring	obscure	VERB	VBG	Tense=Pres|VerbForm=Part	2	advcl	_	_
4	of	of	ADP	IN	_	6	case	_	_
5	the	the	DET	DT	Definite=Def|PronType=Art	6	det	_	_
6	Sun	Sun	PROPN	NNP	Number=Sing	3	obl	_	_
7	by	by	ADP	IN	_	9	case	_	_
8	the	the	DET	DT	Definite=Def|PronType=Art	9	det	_	_
9	Moon	Moon	PROPN	NNP	Number=Sing	3	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **obscure** | gerund |  |  |  |  |  | of the Sun; by the Moon | vn remedy-45.7 «NP V NP.patient»: agent=Agent |

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

<!-- .ven lang=en -->
The rotation of the Earth upon its axis approximately once in twenty-four hours

<!-- fold The tree, 14 words -->
```conllu
# sent_id = question:world:118-day-night-shadows-sundials:e1:o2:1
# text = The rotation of the Earth upon its axis approximately once in twenty-four hours
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	rotation	rotation	NOUN	NN	Number=Sing	0	root	_	_
3	of	of	ADP	IN	_	5	case	_	_
4	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
5	Earth	Earth	PROPN	NNP	Number=Sing	2	nmod	_	_
6	upon	upon	ADP	IN	_	8	case	_	_
7	its	its	PRON	PRP$	Case=Gen|Gender=Neut|Number=Sing|Person=3|Poss=Yes|PronType=Prs	8	nmod:poss	_	_
8	axis	axis	NOUN	NN	Number=Sing	5	nmod	_	_
9	approximately	approximately	ADV	RB	_	10	advmod	_	_
10	once	once	ADV	RB	NumForm=Word|NumType=Mult	2	advmod	_	_
11	in	in	ADP	IN	_	15	case	_	_
12	twenty	twenty	NUM	CD	NumForm=Word|NumType=Card	15	nummod	_	SpaceAfter=No
13	-	-	PUNCT	HYPH	_	12	punct	_	SpaceAfter=No
14	four	four	NUM	CD	NumForm=Word|NumType=Card	12	conj	_	_
15	hours	hour	NOUN	NNS	Number=Plur	2	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **rotate** |  | the Earth upon Earth's axis |  |  |  | in twenty hours |  | nom rotation «act intransitive»: of=agent in=obl |

### Option 3 {#o3}

<!-- .ven lang=en -->
The revolution of the Sun about a stationary Earth once daily

```conllu
# sent_id = question:world:118-day-night-shadows-sundials:e1:o3:1
# text = The revolution of the Sun about a stationary Earth once daily
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	revolution	revolution	NOUN	NN	Number=Sing	0	root	_	_
3	of	of	ADP	IN	_	5	case	_	_
4	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
5	Sun	Sun	PROPN	NNP	Number=Sing	2	nmod	_	_
6	about	about	ADP	IN	_	8	case	_	_
7	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
8	stationary	stationary	NOUN	NN	Number=Sing	2	nmod	_	_
9	Earth	Earth	PROPN	NNP	Number=Sing	8	appos	_	_
10	once	once	ADV	RB	NumForm=Word|NumType=Mult	2	advmod	_	_
11	daily	daily	ADV	RB	_	10	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **revolt** |  | the Sun |  |  |  |  | about a stationary | nom revolution «event intransitive»: of=agent about=obl |

### Option 4 {#o4}

<!-- .ven lang=en -->
The diminution of the Sun's light at fixed hours

```conllu
# sent_id = question:world:118-day-night-shadows-sundials:e1:o4:1
# text = The diminution of the Sun's light at fixed hours
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	diminution	diminution	NOUN	NN	Number=Sing	0	root	_	_
3	of	of	ADP	IN	_	7	case	_	_
4	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
5	Sun	Sun	PROPN	NNP	Number=Sing	7	nmod:poss	_	SpaceAfter=No
6	's	's	PART	POS	_	5	case	_	_
7	light	light	NOUN	NN	Number=Sing	2	nmod	_	_
8	at	at	ADP	IN	_	10	case	_	_
9	fixed	fix	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	10	amod	_	_
10	hours	hour	NOUN	NNS	Number=Plur	2	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **fix** | participle |  |  |  |  |  |  | vn shake-22.3-2 «NP V ADV-Middle»: agent=Patient |
| 2 | **diminish** |  | the Sun's light |  |  |  | at fixed hours |  | nom diminution «process intransitive»: of=agent at=obl |
| 3 | **light** |  | the Sun |  |  |  |  |  | nom light «phenomenon transitive»: poss=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.

<!-- /div -->

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- ← previous: [Day and night, shadows and sundials, test 11](https://md.mova.elamur.ai/free/en/corpora/questions/world/118-day-night-shadows-sundials/t11/)
- next →: [Day and night, shadows and sundials, exam 2](https://md.mova.elamur.ai/free/en/corpora/questions/world/118-day-night-shadows-sundials/e2/)
- ↑ back to [Day and night, shadows and sundials](https://md.mova.elamur.ai/free/en/corpora/questions/world/118-day-night-shadows-sundials/)