---______ do you exercise? ---Once a week.
---I am going to Mount Tai on Sunday with my parents. ---____________
The girl is young. She doesn’t know the way ______ home.
---It’s so hot. Why not ______ swimming? ---It’s a good idea. Let’s go.
Please be careful when you walk ______ the street. There are so many cars.
---Does Cindy go to school by _____ bus? ---No, she doesn’t. She takes ______ underground.