The factory ______ its waste into the river, but now it deals with the waste in a new way.
A:used to dump
B:is used to dump
C:used to dumping
D:is used to dumping
偏二甲肼(C2H8N2)是神州八号火箭发动机燃料,燃烧时氧化剂是四氧化二氮,反应的化学方程式为C2H8N2 + 2N2O42CO2↑ + 4X+ 3N2↑ ,下列有关说法正确的是( )
千条线,万条线,数不清,剪不断,
落在田间秧苗绿,掉进河里看不见。
谜底是____