Question

Experts have been warning___of the health risks caused by passive smoking.

A．a(chǎn)t a time	B．a(chǎn)t one time
C．for some time	D．for the time

Answer 1

C

for some time 意為“一段時(shí)間”，因?yàn)橹^語用了現(xiàn)在完成進(jìn)行時(shí)，所以要用for some time，表示從過去的某個(gè)時(shí)候開始一直延續(xù)到現(xiàn)在的一段時(shí)間內(nèi)，專家一直警告說被動(dòng)吸煙引起健康危急。at a time意為“每次,在某時(shí)”；at one time意為“同時(shí),曾經(jīng)”；for the time意為“暫時(shí)”。