Mr. Smith works with a mobile phone company but he for this international meeting since

问题补充：

Mr. Smith works with a mobile phone company, but he for this international meeting, since he is on holiday.

A. works

B. is working

C. has worked

D. had worked

答案：

A. works

(答案→)B. is working

C. has worked

D. had worked

解析： 根据since he is on holiday，说明指的是现在的情况，所以用现在进行时态。选B。