题干
It's very useful to ______the correct answers next to the mistakes.
A：take away
B：look up
C：set up
D：write down
答案(点此获取答案解析）
D
It's very useful to ______the correct answers next to the mistakes.
A：take away
B：look up
C：set up
D：write down
2NH3已达到平衡状态的是（ ）