商鞅变法成功的最根本原因是（　　）

    Fire can____ down a lot of trees. It can____ people, too. We must be____with fire. We mustn't____ in the forest. We mustn't play____ fires at home. We mustn't play with matches either.

B

    I'm at Billy's birthday party. There are a lot of friends in his house. Some stand beside the table and enjoy the snacks and drinks. There is some food on the table. I like the chocolate and the fruit very much. Billy sits in the sofa and chats with some friends there. He wears a red T-shirt and a pair of blue jeans. He looks so cool today. Wow! The cake is really big. There are some candles on it. Billy's friends begin to sing 'Happy Birthday' to Billy. Billy is very excited. He blows out the candles (吹蜡烛) and cuts the cake. Everyone has fun at the party.

如图是表示吃酸梅分泌唾液的反射的反射弧结构简图，下列说法不正确的是（  ）