加热炉点火点不着时或者点着又熄灭后应该（）。

A.开大点煤气

B.关小点空气

C.关闭阀门

D.开小点煤气

The prices of beer_____ from 50 cents to $4 per liter during the summer season.[ ]

A. altered      

B. ranged

C. separated      

D. differed