Parents should be________（负责）for their children's studies.
I can't________（买得起）to buy the car, because I don't have enough money.
We are doing a________（调查）about the health problem.
I have taken part in an________（环境的）project since last year.
The table is made of________（金属）.
We can go to the biggest________（宫殿）to sing a song.
