各种管道在自流条件下最小容许流速不得小于()。
A、0.05m/s
B、0.25m/s
C、0.75m/s
D、1.5m/s
参考答案:C
— Excuse me, where is Jim?
— Oh, he ______ dumplings in the kitchen. [ ]
A. makes
B. will make
C. is making
D. made
汽车的构成主要有四个部分组成车身、()、发动机和电器系统。