题干
Water is very dangerous sometimes. So we must be careful ______ it.
A：of
B：with
C：to
D：in
答案(点此获取答案解析）
B
Water is very dangerous sometimes. So we must be careful ______ it.
A：of
B：with
C：to
D：in
2NH3(g) △H <0，在673K、30MPa下n(NH3)和n(H2)随时间变化的关系如下图所示。下列叙述正确的是（ ）