---
title: Pythons have tiny leg bones but no legs. What is the best explanation? — Snakes and lizards · tree and pragmatics
description: Pythons have tiny leg bones but no legs. What is the best explanation? Test 8 · ★★★ of lesson 30 «Snakes and lizards» of the biology 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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# Test 8 · ★★★ · Snakes and lizards

<!-- .ven lang=en -->
Pythons have tiny leg bones but no legs. What is the best explanation?

<!-- .vintro -->
**Mova's choice:** option 2 · **The right answer:** option 1 · wrong ✗ · **Who acts:** Pythons, best explanation · **What happens:** have, be · **To what, where:** tiny leg bones

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This is test 8 · ★★★ of lesson 30 «Snakes and lizards» of the biology 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/biology/30-snakes-and-lizards/#t8).

## The question {#question}

<!-- .note -->
*Sentence 1:* Pythons have tiny leg bones but no legs.

```conllu
# sent_id = question:biology:30-snakes-and-lizards:t8:1
# text = Pythons have tiny leg bones but no legs.
1	Pythons	python	NOUN	NNS	Number=Plur	2	nsubj	_	_
2	have	have	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	tiny	tiny	ADJ	JJ	Degree=Pos	5	amod	_	_
4	leg	leg	NOUN	NN	Number=Sing	5	compound	_	_
5	bones	bone	NOUN	NNS	Number=Plur	2	obj	_	_
6	but	but	CCONJ	CC	_	8	cc	_	_
7	no	no	DET	DT	PronType=Neg	8	det	_	_
8	legs	leg	NOUN	NNS	Number=Plur	5	conj	_	SpaceAfter=No
9	.	.	PUNCT	.	_	2	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **have** | present | Pythons | tiny leg bones but no legs |  |  |  |  | vn birth-28.2-1 «NP V NP»: agent=Agent bone=Patient |

<!-- .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 best explanation?

```conllu
# sent_id = question:biology:30-snakes-and-lizards:t8:2
# text = What is the best explanation?
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	best	good	ADJ	JJS	Degree=Sup	5	amod	_	_
5	explanation	explanation	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 best explanation |  |  |  |  |  | tree rules |

## The options {#options}

### Option 1 · ✓ the right answer {#o1}

<!-- .ven lang=en -->
Their ancestors had legs, and the bones are left over

```conllu
# sent_id = question:biology:30-snakes-and-lizards:t8:o1:1
# text = Their ancestors had legs, and the bones are left over
1	Their	their	PRON	PRP$	Case=Gen|Number=Plur|Person=3|Poss=Yes|PronType=Prs	2	nmod:poss	_	_
2	ancestors	ancestor	NOUN	NNS	Number=Plur	3	nsubj	_	_
3	had	have	VERB	VBD	Mood=Ind|Number=Plur|Person=3|Tense=Past|VerbForm=Fin	0	root	_	_
4	legs	leg	NOUN	NNS	Number=Plur	3	obj	_	SpaceAfter=No
5	,	,	PUNCT	,	_	10	punct	_	_
6	and	and	CCONJ	CC	_	10	cc	_	_
7	the	the	DET	DT	Definite=Def|PronType=Art	8	det	_	_
8	bones	bone	NOUN	NNS	Number=Plur	10	nsubj:pass	_	_
9	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	10	aux:pass	_	_
10	left	leave	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	3	conj	_	_
11	over	over	ADV	RB	_	10	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **have** | past | Their ancestors | legs |  |  |  |  | vn birth-28.2-1 «NP V NP»: agent=Agent leg=Patient |
| 2 | **leave over** | present · passive |  | the bones |  |  |  | over *property* | vn keep-15.2 «NP V NP»: subject=Theme |

### Option 2 · ← Mova's choice {#o2}

<!-- .ven lang=en -->
They are bones from mice they ate

```conllu
# sent_id = question:biology:30-snakes-and-lizards:t8:o2:1
# text = They are bones from mice they ate
1	They	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	3	nsubj	_	_
2	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	cop	_	_
3	bones	bone	NOUN	NNS	Number=Plur	0	root	_	_
4	from	from	ADP	IN	_	5	case	_	_
5	mice	mouse	NOUN	NNS	Number=Plur	3	nmod	_	_
6	they	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	7	nsubj	_	_
7	ate	eat	VERB	VBD	Mood=Ind|Number=Plur|Person=3|Tense=Past|VerbForm=Fin	5	acl:relcl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **is a** | present | They | bones |  |  |  | from mice | tree rules |
| 2 | **eat** | past | mice *= mouse* | mice *not said here* |  |  |  |  | vn eat-39.1-1 «NP V NP»: agent=Agent mouse=Patient |

### Option 3 {#o3}

<!-- .ven lang=en -->
Pythons will grow legs when they are old and too heavy to slide

```conllu
# sent_id = question:biology:30-snakes-and-lizards:t8:o3:1
# text = Pythons will grow legs when they are old and too heavy to slide
1	Pythons	python	NOUN	NNS	Number=Plur	3	nsubj	_	_
2	will	will	AUX	MD	VerbForm=Fin	3	aux	_	_
3	grow	grow	VERB	VB	VerbForm=Inf	0	root	_	_
4	legs	leg	NOUN	NNS	Number=Plur	3	obj	_	_
5	when	when	SCONJ	WRB	_	8	mark	_	_
6	they	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	8	nsubj	_	_
7	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	8	cop	_	_
8	old	old	ADJ	JJ	Degree=Pos	3	advcl	_	_
9	and	and	CCONJ	CC	_	11	cc	_	_
10	too	too	ADV	RB	_	11	advmod	_	_
11	heavy	heavy	ADJ	JJ	Degree=Pos	8	conj	_	_
12	to	to	PART	TO	_	13	mark	_	_
13	slide	slide	VERB	VB	VerbForm=Inf	11	advcl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **grow** | future | Pythons | legs |  |  |  |  | vn appear-48.1.1 «PP.location V NP»: agent=Location leg=Theme |
| 2 | **is** | present | Pythons *= python* |  |  |  |  | old *property* | tree rules |
| 3 | **be** |  | Pythons *= python* *not said here* |  |  |  |  |  | tree rules |
| 4 | **slide** | to-infinitive | Pythons *= python* *not said here* |  |  |  |  |  | vn run-51.3.2-2 «NP V»: agent=Theme |

### Option 4 {#o4}

<!-- .ven lang=en -->
Pythons are growing legs right now

```conllu
# sent_id = question:biology:30-snakes-and-lizards:t8:o4:1
# text = Pythons are growing legs right now
1	Pythons	python	NOUN	NNS	Number=Plur	3	nsubj	_	_
2	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	aux	_	_
3	growing	grow	VERB	VBG	Tense=Pres|VerbForm=Part	0	root	_	_
4	legs	leg	NOUN	NNS	Number=Plur	3	obj	_	_
5	right	right	ADV	RB	_	6	advmod	_	_
6	now	now	ADV	RB	PronType=Dem	3	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **grow** | present · progressive | Pythons | legs |  |  | now |  | vn appear-48.1.1 «PP.location V NP»: agent=Location leg=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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- ← previous: [Snakes and lizards, test 7](https://md.mova.elamur.ai/free/en/corpora/questions/biology/30-snakes-and-lizards/t7/)
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