制冷机组上常用的压差控制器，控制的是机组的（）。
A.吸气压力
B.吸气压力和排气压力的差值
C.排气压力
D.油泵的排出压力和吸入压力的差值
参考答案：D
On receiving the admission letter from Harvard University, _____ that he stood for quite a while speechless. [ ]
A. Bruce was too excited
B. so excited was Bruce
C. so excited Bruce was
D. too excited was Bruce
非零售包装的精制凡士林
