题干
I know Simon is __________ boy. He can swim and ride.
A：a 11-year-old
B：an 11-year-old
C：a 11-years-old
D：an 11-years-old
答案(点此获取答案解析）
B
I know Simon is __________ boy. He can swim and ride.
A：a 11-year-old
B：an 11-year-old
C：a 11-years-old
D：an 11-years-old
学方程式如下：SiCl4(g)＋2H2(g)
Si(s)＋4HCl(g)；ΔH＝＋Q kJ·mol－1(Q>0) ，某温度、压强下，将一定量反应物通入密闭容器进行以上反应(此条件下为可逆反应)，下列叙述正确的是( )
