The letter is from my sister .I receive it yesterday.(合成复合句)

问题描述:

The letter is from my sister .I receive it yesterday.(合成复合句)

Yesterday I received a letter from my sisiter.

The letter that i recerived it yesterday is from my sister.是一个定语从句

The letter that I received yesterday is from my sister.

The letter which I received yesterday was from my sister .