The door ________ open,no matter how hard she pushed. 2.There's no light on—they ________ be at home. 3.—Must he come to sign this paper himself? —Yes, he ________. 4.—Isn't that your teacher over there? —No, it ________ be him. I'm sure he doesn't wear glasses. 5.When we worked in the same office, we ________ often have coffee together. 6.A computer ________ think for itself; it must be told what to do. 7.—Can't you stay a little longer? —It's getting late.I really________go now. My daughter is home alone. 8.You ________ be tired—you've only been working for an hour. 9.Advertisements are powerful and some companies try to mislead us, so we ________ be careful when reading them. 10.—Can I pay the bill by check? —Sorry, sir. But it is the management rules of our hotel that payment ________ be made in cash. 11.I'm going to Europe on vacation together with John if I ________find the money. 12.—To stop the plant from exploding is challenging and demanding. Who do you think can do the job? —________ the brave workers have a try? 13.When winter comes, ________ spring be far behind? 14.—Could I borrow your dictionary? —Yes, of course you ________. 15.—Mum, would you please buy me an iPad? —If you can help do the dishes the whole vacation, you ________ have one as a reward. 16.You've been working all day. You ________ be very tired. 17.(The doorbell rings.) I wonder who that is. It ________ be Lisa. She's still in the library at this time. 18.It is a long time since we met last time. You ________ come and see us more often. 19.I haven't decided where I'm going for my holidays. I ______ go to Australia. 20.—Who was the man talking with your teacher? —I'm not sure. It ________ be her brother.