will you come back?- In an hour.How soon B. How often C. How long D. How far

问题补充：

will you come back? --- In an hour.

How soon B. How often C. How long D. How far

答案：

解析：考查疑问词。How soon多久；How often多久一次；How long多长；How far 多远；根据答语，一小时后。可知问的是你多久后回来？故选A。