It is important to know about the cultural differences that        cause problems.

—Could you please come to the museum with me this afternoon?—Sorry，I ________．I have to take a piano lesson at 2 pm．

Some “healthy” habits, such as shower every day and sitting on the loo, _____ be bad for you.

—— We expected you yesterday.—— I'm sorry,  I______you to say that I couldn't be here until today.

The light is on in Mr. Green’s room. He _______ be at home.