如下各项中,有几项参数的数值增大可能会使离心泵的流量减小?()
①叶轮转速;
②叶片装置角;
③叶片宽度;
④叶轮直径。
A.0
B.1
C.2
D.3
参考答案:B
My good friend Rose went to the party with her husband, ________ a happy evening of wine, food and
song.[ ]
A.expecting
B.to expect
C.expected
D.having expected
叔叔用8根a分米长的钢丝和4根b分米长的钢丝焊成 一个长方体的宠物房框架,它的体积是多少立方分米?[ ]
A.4ab
B.ab2
C.a2b