---
title: The Earth's magnetic poles have swapped places many times in its his… — Compasses and the magnetic Earth · tree and pragmatics
description: The Earth's magnetic poles have swapped places many times in its history, over hundreds of thousands of years. A sentence of the lesson «Compasses and the magnetic Earth» of the physics course of Mova's primary school with its dependency tree and the pragmatics of every clause.
---

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# Compasses and the magnetic Earth, sentence 10

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The Earth's magnetic poles have swapped places many times in its history, over hundreds of thousands of years.

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**What happens:** swap · **To what, where:** magnetic poles, history

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This is a sentence of the lesson «Compasses and the magnetic Earth» of the physics course of Mova's primary school. The page gives its syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause: what happens, when and where, as Mova's frames read it from the tree.

## The tree {#tree}

```conllu
# sent_id = school:physics:030-compasses-and-the-magnetic-earth.lesson:10
# text = The Earth's magnetic poles have swapped places many times in its history, over hundreds of thousands of years.
# source = school lesson (ours)
# course = physics
# lesson = 030-compasses-and-the-magnetic-earth.lesson
# annotation = Mova annot: Rust (en) → Haiku 5.5 (medium, Batches API) patches; gates UD 2.18; agreed by treeagree rules (Stanza, Trankit, spaCy trf): no change
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	Earth	Earth	PROPN	NNP	Number=Sing	5	nmod:poss	_	_
3	's	's	PART	POS	_	2	case	_	_
4	magnetic	magnetic	ADJ	JJ	Degree=Pos	5	amod	_	_
5	poles	pole	NOUN	NNS	Number=Plur	7	nsubj:pass	_	_
6	have	have	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	7	aux	_	_
7	swapped	swap	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
8	places	place	NOUN	NNS	Number=Plur	7	obj	_	_
9	many	many	ADJ	JJ	Degree=Pos	10	amod	_	_
10	times	time	NOUN	NNS	Number=Plur	7	obl:unmarked	_	_
11	in	in	ADP	IN	_	13	case	_	_
12	its	its	PRON	PRP$	Case=Gen|Gender=Neut|Number=Sing|Person=3|Poss=Yes|PronType=Prs	13	nmod:poss	_	_
13	history	history	NOUN	NN	Number=Sing	7	obl	_	_
14	,	,	PUNCT	,	_	16	punct	_	_
15	over	over	ADP	IN	_	16	case	_	_
16	hundreds	hundred	NOUN	NNS	Number=Plur	7	obl	_	_
17	of	of	ADP	IN	_	18	case	_	_
18	thousands	thousand	NOUN	NNS	Number=Plur	16	nmod	_	_
19	of	of	ADP	IN	_	20	case	_	_
20	years	year	NOUN	NNS	Number=Plur	18	nmod	_	_
21	.	.	PUNCT	.	_	7	punct	_	_
```

## Pragmatics {#pragmatics}

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- form: statement
- act: assert
- voice: narrator
- polarity: none
- teacher: kept the draft

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| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **swap** | present · perfect · passive |  | the Earth's magnetic poles |  | Earth's history | time | over hundreds of thousands of years | tree rules |

<!-- .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.

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**Licence: [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/)**, as the whole of Mova corpus 0.4, of which this treebank (the agreed school, `mova-school-agreed-en.conllu`) is part. The lessons were written for Mova's primary school. Sentence `school:physics:030-compasses-and-the-magnetic-earth.lesson:10`.

**The tree:** Mova annot: Rust (en) → Haiku 5.5 (medium, Batches API) patches; gates UD 2.18; agreed by treeagree rules (Stanza, Trankit, spaCy trf): no change. **The frames** are read from the tree by Mova's frames reader (`prag`) when this page is built, the lesson read in order, so a pronoun may be resolved from an earlier sentence.

See the [release 0.4](https://md.mova.elamur.ai/free/en/releases/0.4/).

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