My mother is a great cook and we ________ never get enough of her cookies.

For the safety, everyone _________ obey the traffic rules when he is driving or walking.

I still remember my happy childhood when my mother ______ take me to Disneyland at weekends.

(2013·高考新课标全国卷Ⅱ)Since nobody gave him any help，he________have done the research on his own.

— Can I pay the bill by check? — Sorry, sir. But it's the management rules of our hotel that payment ______be made in cash.