题干
Helen is 15 years old, and Joan is 15, too. So Helen is ____ Joan.
A：as big as
B：as older as
C：as old as
D： so old as
答案(点此获取答案解析）
C
Helen is 15 years old, and Joan is 15, too. So Helen is ____ Joan.
A：as big as
B：as older as
C：as old as
D： so old as
PCl3(g)＋Cl2(g) ②2HI(g)