（1） In short，things have began to improve since schools were called on to reduce learning load．（应为：begun）

（2） I was studing in my room when the telephone rang．（应为：studying）

（3） The taxi driver drived so fast that the car knocked into a truck．（应为：drove）

（4） That afternoon I went swiming together with my friend，Li Dong．（应为：swimming）