— It's hot.
A:kinds of
B:a little
C:a little of
D:a kind of
火药和火药武器传入阿拉伯和欧洲的时间是( )
—School is_________. Let's go to the playground.—OK.
“m=-1”是“直线mx+2m-1y+2=0与直线3x+my+3=0垂直”的( )