It was 80 years before Christopher Columbus crossed the Atlantic______ Zheng sailed to East Africa
| A．when |
| B．that |
| C．after |
| D．since |
______ it is to learn English on the internet!
| A．What a fun | B．What fun | C．How a fun | D．How fun |
Would you____holding this box for me while I open the door?
| A．care | B．like | C．mind | D．matter. |
Most of us know we should cut down fat, but knowing such things isn’t much help when it____shopping and eating.
A refers to B. speaks of C. focuses on D. comes to
He didn't realize he had forgot his bag _____ the plane had taken off.
| A．unless | B．until | C．if | D．or |
_____ of the new aircraft will start next year.
| A．produce | B．production | C．product | D．productive |