---
title: Identify the principal reason for which a waterfall forms in the cou… — Rivers shaping the land · tree and pragmatics
description: Identify the principal reason for which a waterfall forms in the course of a river. Exam question 1 of lesson 53 «Rivers shaping the land» of the geography 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 · Rivers shaping the land

<!-- .ven lang=en -->
Identify the principal reason for which a waterfall forms in the course of a river.

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

<!-- .vabout -->
This is exam question 1 of lesson 53 «Rivers shaping the land» of the geography 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/geography/53-rivers-shaping-the-land/#e1).

## The question {#question}

```conllu
# sent_id = question:geography:53-rivers-shaping-the-land:e1:1
# text = Identify the principal reason for which a waterfall forms in the course of a river.
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	9	obl	_	_
7	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
8	waterfall	waterfall	NOUN	NN	Number=Sing	9	nsubj	_	_
9	forms	form	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	acl	_	_
10	in	in	ADP	IN	_	12	case	_	_
11	the	the	DET	DT	Definite=Def|PronType=Art	12	det	_	_
12	course	course	NOUN	NN	Number=Sing	9	obl	_	_
13	of	of	ADP	IN	_	15	case	_	_
14	a	a	DET	DT	Definite=Ind|PronType=Art	15	det	_	_
15	river	river	NOUN	NN	Number=Sing	12	nmod	_	SpaceAfter=No
16	.	.	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 | **form** | present | a waterfall |  |  | the course of a river |  | for the principal reason | vn appear-48.1.1 «NP V PP.location»: agent=Theme in course=Location |

<!-- .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 -->
Aquatic creatures excavate the riverbed

```conllu
# sent_id = question:geography:53-rivers-shaping-the-land:e1:o1:1
# text = Aquatic creatures excavate the riverbed
1	Aquatic	aquatic	ADJ	JJ	Degree=Pos	2	amod	_	_
2	creatures	creature	NOUN	NNS	Number=Plur	3	nsubj	_	_
3	excavate	excavate	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	the	the	DET	DT	Definite=Def|PronType=Art	5	det	_	_
5	riverbed	riverbed	NOUN	NN	Number=Sing	3	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **excavate** | present | Aquatic creatures | the riverbed |  |  |  |  | vn search-35.2 «NP V NP PP.theme»: agent=Agent riverbed=Location |

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

<!-- .ven lang=en -->
A stratum of resistant rock overlies a less resistant stratum

```conllu
# sent_id = question:geography:53-rivers-shaping-the-land:e1:o2:1
# text = A stratum of resistant rock overlies a less resistant stratum
1	A	a	DET	DT	Definite=Ind|PronType=Art	2	det	_	_
2	stratum	stratum	NOUN	NN	Number=Sing	0	root	_	_
3	of	of	ADP	IN	_	6	case	_	_
4	resistant	resistant	ADJ	JJ	Degree=Pos	6	amod	_	_
5	rock	rock	NOUN	NN	Number=Sing	6	compound	_	_
6	overlies	overlie	NOUN	NNS	Number=Plur	2	nmod	_	_
7	a	a	DET	DT	Definite=Ind|PronType=Art	10	det	_	_
8	less	less	ADJ	JJR	Degree=Cmp	10	amod	_	_
9	resistant	resistant	ADJ	JJ	Degree=Pos	10	amod	_	_
10	stratum	stratum	NOUN	NN	Number=Sing	6	nmod	_	_
```

<!-- .note -->
The frames reader finds no event or fact in this sentence.

### Option 3 {#o3}

<!-- .ven lang=en -->
The river is subjected to a sudden decrease in temperature

```conllu
# sent_id = question:geography:53-rivers-shaping-the-land:e1:o3:1
# text = The river is subjected to a sudden decrease in temperature
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	river	river	NOUN	NN	Number=Sing	4	nsubj	_	_
3	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	aux:pass	_	_
4	subjected	subject	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
5	to	to	ADP	IN	_	8	case	_	_
6	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
7	sudden	sudden	ADJ	JJ	Degree=Pos	8	amod	_	_
8	decrease	decrease	NOUN	NN	Number=Sing	4	obl	_	_
9	in	in	ADP	IN	_	10	case	_	_
10	temperature	temperature	NOUN	NN	Number=Sing	8	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **subject** | present · passive |  | the river |  |  |  | to a sudden decrease in temperature | tree rules |

### Option 4 {#o4}

<!-- .ven lang=en -->
The river attains its greatest width

```conllu
# sent_id = question:geography:53-rivers-shaping-the-land:e1:o4:1
# text = The river attains its greatest width
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	river	river	NOUN	NN	Number=Sing	3	nsubj	_	_
3	attains	attain	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	its	its	PRON	PRP$	Case=Gen|Gender=Neut|Number=Sing|Person=3|Poss=Yes|PronType=Prs	6	nmod:poss	_	_
5	greatest	great	ADJ	JJS	Degree=Sup	6	amod	_	_
6	width	width	NOUN	NN	Number=Sing	3	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **attain** | present | the river | river's greatest width |  |  |  |  | vn get-13.5.1 «NP V NP»: agent=Agent width=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.

<!-- /div -->

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- ← previous: [Rivers shaping the land, test 11](https://md.mova.elamur.ai/free/en/corpora/questions/geography/53-rivers-shaping-the-land/t11/)
- next →: [Rivers shaping the land, exam 2](https://md.mova.elamur.ai/free/en/corpora/questions/geography/53-rivers-shaping-the-land/e2/)
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