对往复泵产生振动的原因说法不正确的是()。
A、底座松动
B、泵内有气体
C、发生气蚀
D、泵轴与电机轴不在同一中心线
参考答案:C
对往复泵产生振动的原因说法不正确的是()。
A、底座松动
B、泵内有气体
C、发生气蚀
D、泵轴与电机轴不在同一中心线
参考答案:C
阅读下面短文,从每题所给的A、B、C、D四个选项中,选出最佳选项. | ||||
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1. Kids can _____ by reading Fun with Food. | ||||
A. do science experiments B. get cooking experience,, C. cook well in the kitchen D. play some riddle games | ||||
2. _____ has over sixty pages. | ||||
A. Fun with Food B. Kids Cooking lesson E-Book C. Food Facts E-Book D. Kids Food .Science Experiments | ||||
3. Kids Cooking Lessons E-Book is popular because . | ||||
A. there is a unit for each age group B there are a lot of photo tests in it C kids can learn more about science D each part is very easy to print off |