不对,后面的引导词when应该改成that,这是一个强调句型

It is(was)被强调部分...that.(who).句子其余部分...

例如:

I saw her in the park last week.上星期我在公园见到了她

A强调主语我：It was I that /who saw her in the park last week.是我上星期在公园见到了她.

B强调宾语她：It was her that /who I saw in the park last week上星期我在公园见到的是她.

C 强调时间：It was last week that I saw her in the park .是上星期我在公园见到了她.

D强调地点：It was in the park that I saw her last week.上星期我是在公园见到了她.

注意：1.被强调的部分是人时,后面的连接词可以是that,也可以是who：被强调的是其余部分时,哪怕是时间状语和地点状语,一律只能用that,不能用when或where.

2.在这个强调句型中,去掉It is(was)...that.(who）,句子还是一个很完整的句子.上面的例句你可以试着去掉,看看是否如此.

原句修改后变成：it was three years ago that i last visited you .我上一次见你是在三年前了.