题干
一 My cousin is a clever boy and he is good at math.
一 So he is.
A：is worried about
B：does well in
C：is interested in
答案(点此获取答案解析）
B
一 My cousin is a clever boy and he is good at math.
一 So he is.
A：is worried about
B：does well in
C：is interested in
2NH3达到平衡的标志是
