Kim wanted to buy ___________ gifts for her sister.[ ]
A. some
B. a
C. many
答案:A
The students are _____ a good time. [ ]
A. have
B. /
C. having
水源热泵间接供水方式的优点是______。
A.无需二次换热B.水的温度有利于提高热泵效率C.水源的水质不会对板式换热器以外的设备产生不良影响D.系统较简单