I haven't heard from Kate ____ she went to Canada 究竟是after还是sinceI haven't heard from Kate ____ she went to Canada 究竟是after还是since 这句子本来就没时间段啊,怎么选啊
问题描述：
I haven't heard from Kate ____ she went to Canada 究竟是after还是since
I haven't heard from Kate ____ she went to Canada 究竟是after还是since 这句子本来就没时间段啊,怎么选啊
答
since
答
since 这是since的一个典型用法，主句I haven't heard from Kate 用完成时，从句she went to Canada用一般过去式。
答
since . "she went to Canada "就是个时间点。
答
since
since +时间点（短语或从句） 表示的是时间段，与现在完成时连用
答
since,用在完成时中,表示自从,后面接过去式的句子做状语,而主句用现在完成时.