The number of the books in our school library _______ about50,000.
| A．are | B．has | C．have | D．is |
Air pollution does harm to people’s health.
A. very B. little C. great
.I'm sorry you've missed the train .It _______ for 10 minutes .
A. has left B. has been away from C.has been away
---- What are you going to do this weekend ?
---- I'm going to do some outdoor activities _______ it rains .
A. If B. unless C. because
She has succeeded in _____ the problem.
A. solving B.solve C.to solve
---- Would you like a hamburger or a hot dog ?
----_______ is OK . I really don't mind .
A. Either B. None C. Neither