问题
选择题
-- _________ will the foreign students be back from Nanjing?
--In two days, I think.
A．How soon
B．How often
C．How fast
D．How long
答案
答案：A
疑问词辨析. How soon 多久; How often 多久一次;How fast多快;How long多长.
根据答语,两天以后，可知上文对将来时间进行提问，故用how soon来提问。选A.