溴化锂吸收式制冷机的屏蔽通常为立式和卧式两种、泵轮部分的结构类似于一般的（）。
A.活塞式0压缩机
B.离心泵
C.齿轮泵
D.真空泵
参考答案：B
— Why didn’t you go to the cinema yesterday?
— I ____, but my wife returned from France the moment I was leaving.
A．was going to
B．would
C．did
D．had
政府采购合同的补充合同的采购金额不得超过原合同采购金额的（）。
A.20%
B.15%
C.12%
D.10%
