如图,AB是⊙O的弦,OC⊥AB于点C,若AB=4,OC=1,则⊙O的半径为( )
A:3
B:5
C:25
D:6
如图所示,闭合开关,滑动变阻器滑片向左移动过程中( )
河南省开封市西北,有一座5A级风景区一清明上河园。有一片建筑高挂“瓦子”的标志,瓦子是北宋东京城里( )
将正确的图片和句子配对
① It's yellow. It's small. It goes “Peep,peep”.
② It's fat. It goes “Oink… oink”.
③ It's big. It goes “ Moo…moo”.
④ It's thin. It's in the tree.
⑤ It's yellow. It goes “ Quack …quack”.
____ ____ ____ ____ ____
算一算
25×80=2000
(25×5)×(80÷5)=____
(25÷5)×(80×5) =____