_____ the environment is important for human beings.
| A．Take care of | B．Taking care of |
| C．Took care of | D．Take the care of |
If you _______ , I will _______ myself.
| A．don’t come; mop up it | B．don’t come; mop it up |
| C．won’t come; mop up it | D．won’t come; mop it up |
-- Can I join their club?
-- I am afraid you will be refused __________ you’ve passed all their tests.
| A．if | B．although |
| C．unless | D．since |
He fell off the bike ________.
| A．while he rode | B．while he was riding |
| C．while he is riding | D．while on bike |
My sister isn’t in. ________ she comes back, I’ll let her call you back.
| A．While | B．Until | C．Before | D．When |
She got up early this morning _________ she could catch the first bus.
| A．because | B．so that |
| C．in order to | D．when |