I. 单项选择 (共15小题; 每小题1分, 满分15分)
1. Boys and girls, keep calm and be confident. I am sure all of you are __________ excellent students.
A. a B. an C. the D. /
2. Look! The little dog can walk ________ two legs.
A. at B. in C. with D. on
3. Tomorrow we will have a soccer game. We must do ________ best to win the game.
A. us B. our C. we D. ours
4. This morning Sally went to the shopping centre in such a hurry that she________ the key at