did Charles Smith hiccup?- For about two weeks.A. WhenB. HowC. How longD. How ofte

问题补充：

--- did Charles Smith hiccup? --- For about two weeks.

A. When

B. How

C. How long

D. How often

答案：

A. When

B. How

(答案→)C. How long

D. How often

解析：疑问词辨析。When什么时候；How怎样；How long多长；How often多久一次。根据答语，大约两周。可知前文提问时间长短，故选C。