My mother _____ 160 yuan on this skirt. [ ]
A. cost
B. paid
C. took
D. spent
答案:D
--How did he get infected?
--She ____the viruses without any protection.
A.exposed to
B.had exposed to
C.was exposed to
D.had been exposed
电阻应变式称重传感器主要由弹性元件、()和测量电路组成。