— The floor is dirty. Would you please _?
— With pleasure.
| A．mop it up | B．mop up it |
| C．to mop it up | D．to mop up it |
Now my father __________ his bike to work every day instead of driving.
| A．ride | B．rode | C．rides | D．will ride |
By the end of the last month, I _____________ all the CDs of Justin Bieber.
| A．collect | B．collected | C．have collected | D．had collected |
You _________lose your way if you walk alone in the mountains at night.
A. may B need C. should D. ought to
We didn’t start our discussion __________ everybody arrived.
| A．since | B．if | C．while | D．until |
Take the exam carefully, _______ you won’t get full marks.
| A．but | B．and | C．or | D．so |