互动封闭仿真课堂1、智能交互 2、电子板书式视频教学 3、5分钟一次互动问答 4、封闭课堂
1. If I ____ where he lived， I ____ a note to him.
A. knew， would
B. had known， would have sent
C. know， would send
D. knew， would have sent
2. If they ____ earlier than expected， they ____ here now.
A. had started， would be
B. started， might be
C. had started， would have been
D. will start， might have been
3. I didn't know his telephone number. ____ it， I ____ then.
A. Had I known， would ring him up
B. Should I know， would have rung him up
C. If I knew； would ring him up
D. Had I known； would have rung him up