混合冷剂阶式制冷循环可采用单级压缩，比阶式制冷循环过程投资费用（）。
A.稍高
B.低
C.相同
D.高得多
参考答案：B
The comments the expert made _____ stock market bothered Bill greatly, _____ him sleepless all night.[ ]
A. concerning; making
B. be concerning; which made
C. concerned; made
D. to be concerning; made
建筑工地上用以拌制混合砂浆的石灰膏必需经过一定时间的陈化，这是为了消除( )的不利影响。
A．生石灰 B．欠火石灰 C．过火石灰 D．石灰石
