单选题 根据下面短文回答下列问题。
People are busy working every day, so they do not have enough time to do exercises. As a result(结果), many people become too fat or too thin. To keep our bodies healthy, we have to do exercises every day.
There are many kinds of exercises. Bending(弯腰) and stretching(伸展) helps us move easily. Before we play ball games or swim, it is better for us to do bending and stretching exercises first. This kind of exercise is sometimes called warm-up exercise. Running is also a good exercise. If we cannot run fast, we can jog. Jogging means running slowly. Again, before we run or jog, we must do warm-up exercises. Also, we should not run or jog in busy streets. The air there is often dirty. Some people like weight lifting(举重) because it can make their bodies strong. Also, we need to do some warm-up exercises before weight lifting.

单选题 ______ makes many people too fat or too thin.
A. Eating or drinking too much
B. Having no time to do exercises
C. Doing more exercises

单选题 ______ is called warm-up exercises.
A. Playing ball games
B. Weight lifting
C. Bending and stretching