I often watch my cat ______ with a ball. [ ]
A. play
B. plays
C. to play
D. playing
答案:A
PMS系统中房费由夜审房费、()构成。
A.早到房费
B.晚退房费
C.手工房费
资本要素在国际间的流动构成了国际投资的基础。