女士如佩戴耳钉，直径应不超过多少（）
A、1cm
B、2cm
C、3cm
参考答案：A
Tourism is the ______ for the country's economy, so its government tries its best to ______ both
the natural scenery and the places of interest. [ ]
A. center; protect
B. heart; reserve
C. focus; keep
D. engine; preserve
下列哪款飞机是中国首次自行研制、自行制造的大型喷气式客机？（）
A.运-5
B.运-7
C.运-8
D.运-10
