当我们使用"be+doing+sth.when…"的结构时,表示某人正在做某事,这时发生了另一件事情。例如:
She was studying when the phone rang.(电话响时,她正在学习。)
They were playing soccer when it started raining.(开始下雨时,他们正在踢足球。)
关于"with+复合结构",这个结构通常用来描述某人或某物具有某种特征或状态。例如:
He walked into the room with a big smile on his face.(他面带微笑走进房间。)
She entered the party with a beautiful dress.(她穿着漂亮的裙子进入派对。)
至于现在分词用"be",这是现在进行时的一种形式,表示正在进行的动作或状态。例如:
They are studying for the exam.(他们正在为考试而学习。)
She is reading a book.(她正在读一本书。)