1. He is very stubborn, it is impossible to argue _____________ what he doesn’t want to.
A. with him about     B. against him about    C. him into doing    D. him to do
2. Do you know the _________ of the saying I just quoted?
A. resource      B. source      C. course      D. cause
3. –What do you think the noise was?
   --It ___________ a cat.
A. may be       B. might be      C. could have been      D. might have been