--When did you become a volunteer for the elderly?
-- Two years ago. I ______ this group since then.
| A．joined | B．took part in | C．have joined | D．have been in |
Could you please ___ your room after school?
| A．to clean | B．cleaning | C．clean | D．cleans |
—_____ you please play tennis with me? —Sorry, I _____.
| A．Could; can’t | B．Could; couldn’t | C．Can; don’t | D．Can; couldn’t |
Smoking is bad for your health. You should.
| A．give up it | B．give up them | C．give it up | D．give them up |
Aron water five days later.
| A．ran out | B．used out | C．ran out of | D．used out of |
This is______difficult problem that few students can work it out.
| A．so | B．so a | C．such | D．such a |