细胞膜结构有两个最基本的特征()
A.韧性和膜的对称性
B.粘性和膜的对称性
C.粘性和膜的不对称性
D.流动性和膜的对称性
E.流动性和膜的不对称性
参考答案:E
The world's first flying car has been ________ for sale at £800,000 by Courtesy Aircraft of the US.
A.taken up
B.put up
C.pulled up
D.made up
一动圆的圆心在抛物线y2=8x上,且动圆恒与直线x+2=0相切,则动圆必过定点( )
A.(4,0)
B.(2,0)
C.(0,2)
D.(0,-2)