I am so tired for I English for 2 hours.A. is studying　B. have been studyingC. was studyi

问题补充：

I am so tired，for I English for 2 hours.

A. is studying

B. have been studying

C. was studying

D. had been studying

答案：

A. is studying

(答案→)B. have been studying

C. was studying

D. had been studying

解析：句意：我好累，因为我已经学习英语两个小时了。根据“for 2 hours”可知，此处表示动作从过去某一时间开始，一直延续到现在，可能还要继续下去，故应用现在完成进行时。