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| multiple-frequency | |||
| harmonic frequency | |||
| overtone frequency | |||
| 谐波频率: 21 phrases in 9 subjects |
| Air defense | 1 |
| Automobiles | 1 |
| Aviation | 1 |
| Electric machinery | 1 |
| Electronics | 6 |
| Information technology | 1 |
| Mathematics | 3 |
| Technology | 5 |
| Telecommunications | 2 |
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