of和for和by和from的用法与区别

　　The homework was assigned by the teacher.   这些家庭作业是老师布置的。

　　They crossed the river by ferry.   他们乘渡船过了河。

　　She took my umbrella by mistake.   她误拿了我的伞。

　　This is one of the most commonly used methods.这是最常采用的方法之一。

　　I never know what to expect from one day to the next.一天又一天我不知道该期待什么。