--- Look! It ____ be Jack on the playground. ---It ____ be him. Because I saw him enter the school library just now. A. may; mustn’t B. must; can’t C. can; can’t
--- Excuse me. I want to buy some stamps. Where can I find a post office? ---I know ____ not far from here. You can easily find ____. A. that; it B. it; one C. one; it