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| 美国贝尔系统1984 年解体，现为 AT&T | |||
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| 贝尔系统 | |||
| 钟的安装 | |||
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Bell System : 31 phrases in 9 subjects |
| Earth sciences | 1 |
| Electronics | 9 |
| General | 1 |
| Metallurgy | 10 |
| Nautical | 3 |
| Oil / petroleum | 1 |
| Space | 1 |
| Technology | 3 |
| Telecommunications | 2 |
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