______ is known to us is that tobacco contains nicotine and other harmful products, so you should give up smoking.
—I bought this shirt for 35 yuan yesterday. —It’s on sale today for only 29. You should have waited. —Oh, really? But how ________ I know?
How can I ever concentrate if you ________ continually ________ me with silly questions?
—Excuse me, sir. Would you do me a favor? —Of course. What is it? —I ________ if you could tell me how to fill out this form.
—Which flight ________ ? —I want to catch the 13:00.
—You must have met him the other day. —Oh, no, I ________ .