一个英语语法题a rhyme may be passed on with the hour it is learnt.it is learnt 前面为什么不用加when
问题描述：
一个英语语法题
a rhyme may be passed on with the hour it is learnt.it is learnt 前面为什么不用加when
答
我觉得这句话想说的应该是a rhyme may be passed on with the hour spent to learn it。所以这里hour其实就是time的意思，所以是不可以用when来引导的，因为这里不是during that hour, the rhyme is learnt，而是指(the person) spent an hour to learn the rhyme。
答
定语从句中的when可以省略.