社会主义初级阶段的主要矛盾是(   )

Miss Fang: Hello, children. This is Mr. Xu. He's a fireman. Let's welcome Mr. Xu.

Mr. Xu: Thanks. Let's talk about ____safety today. Fire can burn down trees. It can ____people, too. We must be ____with fire. What mustn't we do in the forest or at home, children?

Peter: We mustn't ____in the forest.

Kitty: We mustn't play near fires or play with ____at home.

Mr. Xu: Very good. Safety first.

如图所示，有一水平方向的匀强电场，场强大小为9000N/C，在电场内一水平面上作半径为10cm的圆，圆上取A、B两点，AO沿E方向，BO⊥OA，另在圆心处放一电量为10^﹣8C的正点电荷，则A处场强大小E_A为零．____ （判断对错）