把主動語態(tài)改為被動語態(tài),可以遵循以下幾個步驟：
1.把賓語變成被動語態(tài)中的主語；
2.找出謂語動詞,變成相應的被動.如：一般式變成be done.過去式變成was/were done；
3.把主語變成介詞by 的賓語；
4.注意人稱、時態(tài)和數的變化.
例：1.Bruce writes a letter every week.→A letter is written by Bruce every week.
2.Li Lei mended the broken bike this morning.→The broken bike was mended by Li Lei this morning.
3.He has written two novels so far.→Two novels have been written by him so far.
4.They will plant ten trees tomorrow.→Ten trees will be planted by them tomorrow.
5.Lucy is writing a letter now.→A letter is being written by Lucy now.
6.You must lock the door when you leave.→the door must be locked when you leave.