一道简单的高一英语题，请各位英语高手帮忙做一下，谢谢！

1.The person was willing to help.
The person to which he talked was willing to help.
The person with whom he came was willing to help.

2.The room was dusty.
The room in which he was staying was dusty.
The room to which he was assigned was dusty.

3.The time was very pleasant.
The time when we were still together was very pleasant.
The time about which you wrote was very pleasant.

4.The reason was known to all.
The reason why he was late was known to all.
The reason for which you asked of him was known to all.

S1: The room was dusty.
S2: The room in which I stayed last night was dusty
S3: The room to which I was assigned last night was dusty.
S4: The room outside which I was waiting last night was dusty.