我国已禁止生产、进口、销售含铅的汽油,其主要目的是( )
A:提高汽油的燃烧利用率
B:减少汽车尾气对大气的污染
C:消除噪音
D:降低汽油价格
It's surprising that your brother Russian so quickly—he hasn't lived there very long.