Jawaban:

1. Yesterday I ran into an old friend whom I hadn't seen for years.
2. The class was too large, so it was divided into two sections.
3. I didn't expect to see Joe come to the meeting, but he was there. I was surprised to see him there.
4. The hotel at I stayed was in the middle of the city.
5. She told me about the letter which she wrote to her parents yesterday.

Penjelasan:

1. whommenggantikanhim. ga perlu pakai object pronoun (me, you, him, her, it, them) lagi
2. kelasnya dipisah (be divided) bukan memisahkan diri (divide)
3. see + objective pronoun + infinitive (contoh: see him come, see it go, see me die, etc.)
   surpriseddi sini adalahadjective (saya terkejut; I am surprised) bukanverb(saya mengejutkan (seseorang); I surprise (someone)) jadi pakai be (was surprised)
4. prepositionmengikutiverb (contoh: the place I stay at, the room I stay in, the person I stay with)
5. where khusus untuk tempat (contoh: the city where he lived)