人体运动系统的组成不包括( )
The teacher took my hand in h____ and said “keep on going never give up” .
解一元二次方程x2-2x-5=0,结果正确的是( )
如图所示,在四边形ABCD中,∠D=2∠B,且AD=1,CD=3,cos∠B=33
(1)求△ACD的面积;
(2)若BC=23,求AB的长.