What do you think of the new bridge? —I have never seen _____ before.

Can you tell me what time the flight to Detroit leaves? —I’m sorry, but it ______．

Spacecraft “Discovery” has failed in the course of launch. —-_______? They have been preparing for the test.

Would any one of you please tell me ______ to the railway station?

Why is the classroom so dirty?—Sorry，sir. Ityesterday, We forgot to do it.