I was chatting with my mother on the phone __we were suddenly but off .A.when B.who C.where D.why
问题描述：
I was chatting with my mother on the phone __we were suddenly but off .A.when B.who C.where D.why
答
A答案。原句应该为I was chatting with my mother on the phone when we were cut off suddenly
答
选A
I was chatting with my mother on the phone __we were suddenly but【是cut吧？】 off.
当我们突然被切断时，我和妈妈正在电话上聊天。
其他三项都不符合语境，一个一个说：
不可能是who，因为we were cut off 是一个完整句，不需要who作为宾语或短语的成分出现
不可能是where，整句话都没有地点或暗示地点的词语出现
不可能是why，一般why用于发起特殊疑问或者That‘s why……
答
A。 有三种时态常和when连用——过去进行时、过去完成时、过去将来时。when 表示就在那时的意思。
答
when. 当我正在跟妈妈讲电话的时候，这时候突然中断了。是个关于时间的定于从句，跟时间有关系。
答
这是固定句式“Sb.was/were doing sth.when sth.happened”的用法,意思是“某人正在做某事的时候,另外一件事情发生了”.