——Do you mind telling us something about this area?——Not at all. ________ of the land in this area _________ covered with trees and grass.
A:Two fifth, is
B:Two fifth, are
C:Two fifths, is
D:Two fifths, are
秒表读数为____ s.
在某气体燃烧的火焰上方罩一个干而冷的烧杯,不久在烧杯内壁有水珠出现,把烧杯迅速倒过来,立即加入少量石灰水,振荡,石灰水变浑浊,则该气体可能是( )