night-time
| F-layer
| night time | |
| lab.law. transp. nautic. | período nocturno |
| F layer | |
| commun. | capa F; región F |
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| período nocturno | |||
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night-time : 5 phrases in 4 subjects |
| Communications | 1 |
| Electronics | 2 |
| Environment | 1 |
| Transport | 1 |