1 My sister is keen on listening to music.
-> enjoy + Ving / N = keen on + Ving / N
2 This is the cheapest house for us to rent.
-> This is + so sánh nhất
3 Why didn't you go to the class meeting last Monday ?
-> Từ để hỏi + trợ đông từ ( not ) + S + Vchính ?
4 If you do more exercise, you won't be overweight.
-> If 1: If + S1 + Vs/es, S2 + will + Vinf