问题
单项选择题
根据流体运动要素是否随时间变化，可以把流体运动分为（）两类。
A.层流和紊流
B.静态流和动态流
C.静止流和运动流
D.稳定流和不稳定流
答案
参考答案：D
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根据流体运动要素是否随时间变化，可以把流体运动分为（）两类。
A.层流和紊流
B.静态流和动态流
C.静止流和运动流
D.稳定流和不稳定流
参考答案：D
| 选择下列词汇或短语完成下面对话。 | |
Kevin: I couldn't _________(1) asleep last night. Tony: Why? Did you watch the World Cup last night? Kevin: No, maybe it's ________ (2) the coming final exam. I can't sleep well before exams. Tony: I think you are too ________(3) about exams. You should try to relax yourself. Kevin: What should I do? Tony: You can listen to some soft ________(4) before you go to bed. Or you can take a walk. Kevin: Thanks for your ________(5). I will try it tonight. Tony: You're welcome. |