流体紊流运动的特征是脉动现象，处理方法是时均法。
A. 对
B. 错
Travelers on a tight____ would choose to go there by train instead of by plane.
Tom was ____ leaving the garden when he heard someone cry: “Isn’t it Tom? I can hardly believe my eyes.”
____ is what we need when we design new products.
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