The actor pretends to be a fierce, bold man, but _____ he is timid and shy.
There’re so many kinds of tape-recorders on sale that I can’t make up my mind _____ to buy.
—How’s your tour around the North Lake? Is it beautiful? —It ________ be, but it is now heavily polluted.
John promised his doctor he _____ not smoke and he has never smoked ever since.
According to the air traffic rules, you ___ switch off your mobile phone before boarding.
When I was young, I was told that I ______ play with matches