题目

It is natural that children are curious (好奇的) about the world around them. For example, they want to know how their hearts beat. They want to know why the ocean water tastes salty.As children grow up, they become curious about different kinds of things. When they are babies, they are interested in the parts of their bodies and in the smiles of their mothers. They become interested in the physical world around them: the plants, the animals, the sky. Later, they become interested in the things that people have made: wheels, bicycles, cars. And when they are adults, their curiosity continue有一木块,如图,点P在平面A′C′内,棱BC平行于平面A′C′,要经过P和棱BC将木料锯开,锯开的面必须平整,有N种锯法,N为(    )A.0                   B.1                C.2                    D.无数