A:F1=mgsinθ
B:F1=
C:F2=mgcosθ
D:F2=
These ____(child)can wash clothes .
——Which sport do you like better, swimming or playing basketball?——I prefer ______ to _______. I don't like water sports.
CO2和O2是自然界中生命活动不可缺少的两种气体,下列说法正确的是 ( )