题干
—Playing chess seems to be very hard, Wei Hua.I don't want________.
—Come on, please.
A：try
B：have a try
C：tried it
D：to try it
答案(点此获取答案解析）
D
2SO３(g) （正反应放热）。下列能判断该反应达到平衡状态的标志是