The twin sisters have learned a lot ________ they came to China.
| A．when | B．after | C．since | D．as soon as |
Mr. Li is one of ____ in our school.
| A．the popular teacher |
| B．popular teachers |
| C．the most popular teachers |
| D．most popular teachers |
Don’t swim here, or you may be ____ .
| A．in danger | B．danger |
| C．safe | D．well |
— What will the weather be like tomorrow? — It might be ____ .
| A．rain | B．sun | C．sunny | D．wind |
I was watching TV ____ the thief came into the house.
| A．when | B．while |
| C．for | D．because |
Look! The boy is sitting ____ a tree.
| A．on | B．in | C．of | D．above |