When Madam Curie did the science experiment again, she was more careful where she_____ a mistake.
| A．made | B．has made | C．was making | D．had made |
It is reported that this kind of vegetables _ a lot of vitamins C.
A. contains B. includes C. holds D. keeps
______ time went by , Herbert could finish all the maths exercises in class.
| A．With | B．As | C．while | D．Since |
Lots of the scientists in our country are working hard to ____the planet Mars .
| A．cover | B．search | C．discover | D． explore |
Look at the notice . You are not allowed ____ the gymnasium without permission.
| A．to enter | B．enter | C．entering | D．for entering |
How are you going to _______ such problems?
| A．do with | B．deal with |
| C．deal | D．do up |