when I was a child ,i often went to visit my grandpa living in the countryside in the summer.
when she studies ,she often puts a cup of water on the desk.
when I was doing my homework, my friend phoned me.
不要老想著跟什么時態(tài),語言是相通的,所有的選擇題其實都是對話的一部分,或者是自我陳述的一部分,你為什么不放在情景里去理解和翻譯呢.語言是不能離開情景的.