---
title: Your mate says a mirror swaps left and right, so why doesn't it swap… — Mirrors, rainbows and the blue sky · tree and pragmatics
description: Your mate says a mirror swaps left and right, so why doesn't it swap up and down? What is the real answer? Test 8 · ★ of lesson 21 «Mirrors, rainbows and the blue sky» of the physics course of Mova's primary school, with the dependency tree and pragmatics of the question and of each option; Mova's c
---

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# Test 8 · ★ · Mirrors, rainbows and the blue sky

<!-- .ven lang=en -->
Your mate says a mirror swaps left and right, so why doesn't it swap up and down? What is the real answer?

<!-- .vintro -->
**Mova's choice:** option 1 · **The right answer:** option 1 · right ✓ · **Who acts:** mate, mirror, real answer · **What happens:** say, swap, leave, not swap up, be · **Speech:** someone speaks here

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This is test 8 · ★ of lesson 21 «Mirrors, rainbows and the blue sky» of the physics 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/physics/21-mirrors-rainbows-and-the-blue-sky/#t8).

## The question {#question}

<!-- .note -->
*Sentence 1:* Your mate says a mirror swaps left and right, so why doesn't it swap up and down?

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:t8:1
# text = Your mate says a mirror swaps left and right, so why doesn't it swap up and down?
1	Your	your	PRON	PRP$	Case=Gen|Person=2|Poss=Yes|PronType=Prs	2	nmod:poss	_	_
2	mate	mate	NOUN	NN	Number=Sing	3	nsubj	_	_
3	says	say	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	a	a	DET	DT	Definite=Ind|PronType=Art	5	det	_	_
5	mirror	mirror	NOUN	NN	Number=Sing	6	nsubj	_	_
6	swaps	swap	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	ccomp	_	_
7	left	leave	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	6	xcomp	_	_
8	and	and	CCONJ	CC	_	9	cc	_	_
9	right	right	ADJ	JJ	Degree=Pos	7	conj	_	SpaceAfter=No
10	,	,	PUNCT	,	_	16	punct	_	_
11	so	so	ADV	RB	_	16	advmod	_	_
12	why	why	ADV	WRB	PronType=Int	16	advmod	_	_
13	does	do	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	16	aux	_	SpaceAfter=No
14	n't	not	PART	RB	Polarity=Neg	16	advmod	_	_
15	it	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	16	nsubj	_	_
16	swap	swap	VERB	VB	VerbForm=Inf	3	parataxis	_	_
17	up	up	ADP	RP	_	16	compound:prt	_	_
18	and	and	CCONJ	CC	_	19	cc	_	_
19	down	down	ADV	RB	_	17	conj	_	SpaceAfter=No
20	?	?	PUNCT	.	_	3	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **say** *speech: assert* | present | Your mate |  |  |  |  |  | vn say-37.7-1-1 «NP V that S»: agent=Agent clause=Topic |
| 2 | **swap** | present | a mirror |  |  |  |  |  | tree rules |
| 3 | **leave** | participle | a mirror *not said here* |  |  |  |  |  | vn escape-51.1-1-1 «NP V»: agent=Theme |
| 4 | **not** **swap up** | present · do-support | mirror |  |  |  |  |  | vn substitute-13.6.2 «NP V PP.co-theme»: 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.

<!-- .note -->
*Sentence 2:* What is the real answer?

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:t8:2
# text = What is the real answer?
1	What	what	PRON	WP	PronType=Int	0	root	_	_
2	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	1	cop	_	_
3	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
4	real	real	ADJ	JJ	Degree=Pos	5	amod	_	_
5	answer	answer	NOUN	NN	Number=Sing	1	nsubj	_	SpaceAfter=No
6	?	?	PUNCT	.	_	1	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **is a** | present | the real answer |  |  |  |  |  | tree rules |

## The options {#options}

### Option 1 · ← Mova's choice · ✓ the right answer {#o1}

<!-- .ven lang=en -->
It swaps front and back, not left and right

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:t8:o1:1
# text = It swaps front and back, not left and right
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	2	nsubj	_	_
2	swaps	swap	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	front	front	NOUN	NN	Number=Sing	2	obj	_	_
4	and	and	CCONJ	CC	_	5	cc	_	_
5	back	back	ADV	RB	_	2	conj	_	SpaceAfter=No
6	,	,	PUNCT	,	_	8	punct	_	_
7	not	not	PART	RB	Polarity=Neg	8	advmod	_	_
8	left	leave	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	2	parataxis	_	_
9	and	and	CCONJ	CC	_	10	cc	_	_
10	right	right	ADJ	JJ	Degree=Pos	8	conj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **swap** | present | It | front |  |  |  |  | vn exchange-13.6.1 «NP V NP»: agent=Agent front=Theme |
| 2 | **not** **leave** | participle |  |  |  |  |  |  | vn escape-51.1-1-1 «NP V»: agent=Theme |

### Option 2 {#o2}

<!-- .ven lang=en -->
Mirrors only work sideways

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:t8:o2:1
# text = Mirrors only work sideways
1	Mirrors	mirror	NOUN	NNS	Number=Plur	3	nsubj	_	_
2	only	only	ADV	RB	_	3	advmod	_	_
3	work	work	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	sideways	sideways	ADV	RB	_	3	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **work** | present | Mirrors |  |  |  |  | sideways *property* | vn employment-95.3 «NP V»: agent=Agent |

### Option 3 {#o3}

<!-- .ven lang=en -->
It does swap up and down if you wait

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:t8:o3:1
# text = It does swap up and down if you wait
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	3	nsubj	_	_
2	does	do	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	aux	_	_
3	swap	swap	VERB	VB	VerbForm=Inf	0	root	_	_
4	up	up	ADV	RB	_	3	advmod	_	_
5	and	and	CCONJ	CC	_	6	cc	_	_
6	down	down	ADV	RB	_	4	conj	_	_
7	if	if	SCONJ	IN	_	9	mark	_	_
8	you	you	PRON	PRP	Case=Nom|Person=2|PronType=Prs	9	nsubj	_	_
9	wait	wait	VERB	VBP	Mood=Ind|Number=Sing|Person=2|Tense=Pres|VerbForm=Fin	3	advcl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **swap** | present · do-support | It |  |  |  |  |  | vn substitute-13.6.2 «NP V PP.co-theme»: agent=Theme |
| 2 | **wait** *a condition, not said to happen* | present | you |  |  |  |  |  | vn exist-47.1 «NP V»: agent=Theme |

### Option 4 {#o4}

<!-- .ven lang=en -->
Gravity stops it swapping up and down, but not sideways

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:t8:o4:1
# text = Gravity stops it swapping up and down, but not sideways
1	Gravity	gravity	NOUN	NN	Number=Sing	2	nsubj	_	_
2	stops	stop	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	it	it	PRON	PRP	Case=Acc|Gender=Neut|Number=Sing|Person=3|PronType=Prs	2	obj	_	_
4	swapping	swap	VERB	VBG	VerbForm=Ger	2	xcomp	_	_
5	up	up	ADV	RB	_	4	advmod	_	_
6	and	and	CCONJ	CC	_	7	cc	_	_
7	down	down	ADV	RB	_	5	conj	_	SpaceAfter=No
8	,	,	PUNCT	,	_	11	punct	_	_
9	but	but	CCONJ	CC	_	11	cc	_	_
10	not	not	PART	RB	Polarity=Neg	11	advmod	_	_
11	sideways	sideways	ADV	RB	_	2	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **stop** | present | Gravity | it |  |  |  | sideways *property* | tree rules |
| 2 | **swap** | gerund | Gravity *not said here* |  |  |  |  |  | vn substitute-13.6.2 «NP V PP.co-theme»: 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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