题目内容

螺纹按照牙型可分为粗牙螺纹和细牙螺纹。

A. 对
B. 错

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M为管螺纹代号。

A. 对
B. 错

通常情况下,紫外光区与可见光区的波长范围分别是

A. 200nm-400nm; 400nm-800nm
B. 200nm-400nm; 400nm-600nm
C. 100nm-360nm; 400nm-800nm
D. 100nm-360nm; 360nm-600nm

当吸光度A=0时,则透光率T/%=()

A. 50
B. 20
C. 1
D. 100

--- Tom graduated from college at a very young age.--- Oh, he ______ have been a very smart boy then.

A. could
B. should
C. might
D. must

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