Viết lại câu nghĩa không đổi với gợi ý: Jason was leaving on a flight that was concealed

Đề bài: viết lại câu nghĩa không đổi với gợi ý
1. Jason was leaving on a flight that was concealed ( Which) .........................................................................................
2. I’ve never visited a more impressive exhibition before (that) .........................................................................................
3. None in the club plays tennis as well as David (Who) .........................................................................................
4. We borrowed the money from this bank (Which) .........................................................................................