机械零件的制造包括毛坯成形和（填两个字）加工两个阶段。
生产批量是影响机械零件毛坯选用的因素之一。
A. 对
B. 错
Lesson 7 短听力选择-9[音频]
A. de-icing system failed
B. anti-icing system malfunctioned
C. de-icing truck is out of service
D. weather ahead is deteriorating
Lesson 21 短听力选择-2[音频]
A. Deviation to the right to circumnavigate the bad weather
B. offset left to go round the weather
C. Deviation to the left to avoid the build-up
Descend immediately to detour the CB
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