1.I often go to the supermarket ______ bus. 2.He is going to buy a new book ______ week. 3.The mice are afraid ______ the big cat. 4.______ you are ill, you should see a doctor. 5.In the USA, people ______ bikes must wear a helmet. 6.My teacher is angry ______ Zhang Lingling. 7.We must pay attention ______ the traffic lights.