— does he often go to Beijing?—By plane.A. How B. When C. Where D. Which

问题补充：

— does he often go to Beijing?—By plane.

A. How

B. When

C. Where

D. Which

答案：

(答案→)A. How

B. When

C. Where

D. Which

解析：考查特殊疑问词。句意：---你经常怎样去北京？---乘飞机。对方式进行提问用how.