Section D
Unit 6 Topic 3Bicycle riding is good exercise.
Choose the proper words to complete the sentences with their correct forms.
1. The _________ will become more and more serious if the number of cars and trucks gets larger and larger. 2. I didn’t _______ the traffic signal just now and ran the red light.3. ________ riding caused his injury. 4. Motorcycle riders without ________ will get a fine when riding. 5. Don’t worry about her. She is in ________.  
care         helmet        notice                safe                pollute
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