绢花又称“京花儿”，北京崇文门内的花市大街是当年“京花儿”生产和销售的聚集地。
参考答案：对
I went to Beijing last week. Travelling by _____ plane was quite _____ exciting experience. [ ]
A. a; an
B. /; the
C. the; an
D. /; an
某工厂利用废铁屑与废硫酸起反应来制取硫酸亚铁．现有废硫酸9.8t（H2SO4的质量分数为10%）与足量的废铁屑起反应，可生产硫酸亚铁多少吨？
