一、根据常识，用must或mustn't填空。
1.The traffic(交通) light is red.You cross the street.
2.When you are in the library, you keep quiet.
3.You play with fire. It's dangerous.
4.The floor is wet. You walk slowly.
5.It's time for class. We be late.

1.mustn't 2.must 3.mustn't 4.must 5.mustn't

must表示“必须”，mustn't表示“禁止、不许”，结合常识和规则判断：1.红灯时禁止过马路，填mustn't；2.在图书馆必须保持安静，填must；3.玩火危险，禁止玩火，填mustn't；4.地板湿了必须慢走，填must；5.上课时间不许迟到，填mustn't。

二、Tom 准备了4张图片。请你看一看，为图片选出与其内容相符的句子。

1.()
2.()
3.()
4.()
1.A.They are afraid.They want to give up.
B.They are brave. They always try their best!
2.A.He loves insects. He watches them for hours.
B.He loves plants. He waters them for hours.
3.A.They think people can fly like birds. They try their best.
B.They think people can swim like fish. They play in the water.
4.A.He can't move his head, but he can think about the world.
B.He can move his head easily. He can run very fast.

1.B 2.A 3.A 4.A

1. 第一张图片是女排队员，她们展现出勇敢、尽力的状态，对应选项B；2. 第二张图片是一位在书桌前的人，对应选项A；3. 第三张图片是海滩上的早期飞机，对应选项A；4. 第四张图片是一位不能移动头部但思考世界的人物，对应选项A。