✨ ベストアンサー ✨
前置詞+関係代名詞 を使って一文にまとめる問題ですね。
(1) The friend (with) (whom) I was traveling was able to speak English and French.
(2) This is the program (of) (which) I was speaking.
(3) The woman (with) (whom) I had long carried on a correspondence got married.
(4) Rock-climbing is a sport (in) (which) I am interested.
参考にしてください。