问题补充：
—Sam, come downstairs, please. I need your help.
—Sorry，mum. I on the phone..
A. am talking
B. talked
C. was talking
D. have talked
答案：
(答案→)A. am talking
B. talked
C. was talking
D. have talked
解析：难度适中，考查现在进行时，Sam不能去帮他妈妈，他正在谈电话，答案选A，B是一般过去时，C是过去进行时，D是现在完成时。
如果觉得《—Sam come downstairs please. I need your help.—Sorry mum. I on the phone..A. am talkingB》对你有帮助，请点赞、收藏，并留下你的观点哦！
