---
title: Ascertain the reason for which a straight rod partially immersed in… — Mirrors, rainbows and the blue sky · tree and pragmatics
description: Ascertain the reason for which a straight rod partially immersed in water appears bent. Exam question 4 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 choice was righ
---

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# Exam question 4 · Mirrors, rainbows and the blue sky

<!-- .ven lang=en -->
Ascertain the reason for which a straight rod partially immersed in water appears bent.

<!-- .vintro -->
**Mova's choice:** option 2 · **The right answer:** option 2 · right ✓ · **Who acts:** you, straight rod · **What happens:** ascertain, immerse, appear, bend · **To what, where:** reason, straight rod, water

<!-- .vabout -->
This is exam question 4 of lesson 21 «Mirrors, rainbows and the blue sky» of the physics 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/physics/21-mirrors-rainbows-and-the-blue-sky/#e4).

## The question {#question}

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:e4:1
# text = Ascertain the reason for which a straight rod partially immersed in water appears bent.
1	Ascertain	ascertain	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	3	det	_	_
3	reason	reason	NOUN	NN	Number=Sing	1	obj	_	_
4	for	for	ADP	IN	_	5	case	_	_
5	which	which	PRON	WDT	PronType=Rel	13	obl	_	_
6	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
7	straight	straight	ADJ	JJ	Degree=Pos	8	amod	_	_
8	rod	rod	NOUN	NN	Number=Sing	13	nsubj	_	_
9	partially	partially	ADV	RB	_	10	advmod	_	_
10	immersed	immerse	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	8	acl	_	_
11	in	in	ADP	IN	_	12	case	_	_
12	water	water	NOUN	NN	Number=Sing	10	obl	_	_
13	appears	appear	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	acl	_	_
14	bent	bend	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	13	xcomp	_	SpaceAfter=No
15	.	.	PUNCT	.	_	1	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **ascertain** | imperative | you *not said here* | the reason |  |  |  |  | vn discover-84 «NP V NP»: agent=Agent reason=Topic |
| 2 | **immerse** | participle |  | a straight rod *not said here* |  | water |  | partially *property* | vn put-9.1 «NP V NP PP.destination»: agent=Agent in water=Destination |
| 3 | **appear** | present | a straight rod |  |  |  |  | for the reason | vn seem-109-1-1-1 «NP V S\_INF»: agent=Theme clause=Attribute |
| 4 | **bend** | participle | a straight rod *not said here* |  |  |  |  |  | vn assuming\_position-50 «NP V»: agent=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 {#o1}

<!-- .ven lang=en -->
The rod is deformed by the pressure of the water

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:e4:o1:1
# text = The rod is deformed by the pressure of the water
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	rod	rod	NOUN	NN	Number=Sing	4	nsubj:pass	_	_
3	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	aux:pass	_	_
4	deformed	deform	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
5	by	by	ADP	IN	_	7	case	_	_
6	the	the	DET	DT	Definite=Def|PronType=Art	7	det	_	_
7	pressure	pressure	NOUN	NN	Number=Sing	4	obl	_	_
8	of	of	ADP	IN	_	10	case	_	_
9	the	the	DET	DT	Definite=Def|PronType=Art	10	det	_	_
10	water	water	NOUN	NN	Number=Sing	7	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **deform** | present · passive | the pressure of the water | the rod |  |  |  |  | vn turn-26.6.1 «NP V NP»: agent=Agent subject=Patient |
| 2 | **press** |  |  | the water |  |  |  |  | nom pressure «phenomenon transitive»: of=patient |

### Option 2 · ← Mova's choice · ✓ the right answer {#o2}

<!-- .ven lang=en -->
Light changes direction upon passing from water into air

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:e4:o2:1
# text = Light changes direction upon passing from water into air
1	Light	light	NOUN	NN	Number=Sing	2	nsubj	_	_
2	changes	change	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	direction	direction	NOUN	NN	Number=Sing	2	obj	_	_
4	upon	upon	SCONJ	IN	_	5	mark	_	_
5	passing	pass	VERB	VBG	Tense=Pres|VerbForm=Part	2	advcl	_	_
6	from	from	ADP	IN	_	7	case	_	_
7	water	water	NOUN	NN	Number=Sing	5	obl	_	_
8	into	into	ADP	IN	_	9	case	_	_
9	air	air	NOUN	NN	Number=Sing	5	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **change** | present | Light | direction |  |  |  |  | vn dress-41.1.1-1-1 «NP V NP»: agent=Agent direction=Patient |
| 2 | **pass** | gerund | Light *not said here* |  |  | water |  | into air | vn escape-51.1-1-3 «NP V PP.initial\_location PP.destination»: agent=Theme from water=Initial\_Location into air=Destination |

### Option 3 {#o3}

<!-- .ven lang=en -->
The eye cannot perceive objects beneath water

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:e4:o3:1
# text = The eye cannot perceive objects beneath water
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	eye	eye	NOUN	NN	Number=Sing	5	nsubj	_	_
3	can	can	AUX	MD	VerbForm=Fin	5	aux	_	SpaceAfter=No
4	not	not	PART	RB	Polarity=Neg	5	advmod	_	_
5	perceive	perceive	VERB	VB	VerbForm=Inf	0	root	_	_
6	objects	object	NOUN	NNS	Number=Plur	5	obj	_	_
7	beneath	beneath	ADP	IN	_	8	case	_	_
8	water	water	NOUN	NN	Number=Sing	5	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **not** **perceive** | can | the eye | objects |  |  |  | beneath water | vn see-30.1-1 «NP V S»: agent=Experiencer object=Stimulus |

### Option 4 {#o4}

<!-- .ven lang=en -->
The vessel distorts the rod mechanically by means of its curvature

```conllu
# sent_id = question:physics:21-mirrors-rainbows-and-the-blue-sky:e4:o4:1
# text = The vessel distorts the rod mechanically by means of its curvature
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	vessel	vessel	NOUN	NN	Number=Sing	3	nsubj	_	_
3	distorts	distort	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	rod	rod	NOUN	NN	Number=Sing	3	obj	_	_
6	mechanically	mechanically	ADV	RB	_	3	advmod	_	_
7	by	by	ADP	IN	_	8	case	_	_
8	means	mean	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	parataxis	_	_
9	of	of	ADP	IN	_	11	case	_	_
10	its	its	PRON	PRP$	Case=Gen|Gender=Neut|Number=Sing|Person=3|Poss=Yes|PronType=Prs	11	nmod:poss	_	_
11	curvature	curvature	NOUN	NN	Number=Sing	8	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **distort** | present | the vessel | the rod |  |  |  | mechanically *property* | vn knead-26.5 «NP V NP.material»: agent=Agent rod=Material |
| 2 | **mean** | present |  |  |  |  |  | of vessel's curvature | vn intend-61.2-1 «NP V S»: agent=Agent |
| 3 | **curve** |  | vessel |  |  |  |  |  | nom curvature «state 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.

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