Why do English people talk so often about the weather when they start a talk? — Because the weather is a(n) ________ topic (话题).
Is Tom still in New York or already back at home?—I’m not sure _________. I’ll call to make sure.
Read the letter and ________ him.
How long have you been writing letters in English?— .[ ]
The bus is coming. Be careful when you _____the bus.