shall 1必须,应该（用于陈述句的第二、第三人称中,表示命令、决心、意图等）you shall not leave your post.你不得离开岗位.
⑴把直接引语变为间接引语是,要把shall变为should.
He said:"I shall come tomorrow ."变为He said he should go the next day.⑵表示责任,该做没做,用should have done sth.不该做做了,用should not have done sth.