Which of the following may NOT be the way to keep brains alert

A:Chang to a new working environment B:go out for sightseeing C:keep doing everyday work D:doing crosswords

The president (whom) the bank belongs, promised (to keep) all the board members (informed) of (how) the negotiations were going on.

A:whom B:to keep C:informed D:how

(Hard) (as) he worked, (but) Mr. Brown couldn't (keep) the shop properly.

A:Hard B:as C:but D:keep

(Neither) rain (nor) sleet nor (keep) the mailman from his (appointed) rounds.

A:Neither B:nor C:keep D:appointed

The president (whom) the bank belongs, promised (to keep) all the board members (informed) of (how) the negotiations were going on.

A:whom B:to keep C:informed D:how

W: How long can I keep the bookM:______

A:Yes. You can keep it. B:No. I' m afraid you should return it now. C:Three weeks. But you can renew it if you need it for a longer time. D:You can take it at any time you want.

(Hard) (as) he worked, (but) Mr. Brown couldn't (keep) the shop properly.

A:Hard B:as C:but D:keep