下列说法正确的是( )
A:若x-1x-2有意义,则有x≥1且x≠2
B:勾股定理是a2+b2=c2
C:夹在两条平行线间的线段相等
D:a0=1
在日常生活中,人们食用的蔬菜瓜果大多来自于( )
(____)A.Look,what's that?
(____)B.OK.Let's go.
(____)C.Today is fine. Let's go to the zoo.
(____)D.It's a lion.
(____)E.Hello,boys and girls.
(____)F.Hello,Miss Liu.
(____)G.Oh,it's big.
如图,在平行四边形ABCD中,E为AD的中点.已知AO=6cm,则AC的长为( )