空气压缩机必须有（）。 A.压力表 B.湿度表 C.真空表 D.安全阀_爱下问搜题

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问题多项选择题

空气压缩机必须有（）。

A.压力表

B.湿度表

C.真空表

D.安全阀

答案

参考答案：A, B, D

选择题

She _____ on a new novel ever since this summer and it is supposed to _____ at the beginning of 2011.

A. had worked; be published
B. had been working; have published
C. has worked; publish
D. has been working; be published

单项选择题 A1/A2型题

下列染色体中，不出现随体的是（）

A.13号染色体

B.14号染色体

C.15号染色体

D.17号染色体

E.21号染色体