三（2）班有37名同学参加竞赛，其中参加数学竞赛的有27人，参加作文竞赛的有29人，既参加数学竞赛又参加作文竞赛的有多少人？

如图为细胞结构示意图，请据图回答：

名著阅读。

已知A、B为单质，C为化合物，它们之间存在如下转化关系则下列说法中正确的是（   ）

①若C溶于水后得到强碱溶液，则A可能是Na
②若向C溶液中逐滴加入NaOH溶液的过程中，溶液中出现白色沉淀并逐渐消失，则A可能Al
③若C的溶液遇NaHCO₃固体，放出CO₂气体，则A可能是H₂
④若C的溶液中滴加KSCN溶液显红色，则B可能为Fe
⑤若C的溶液中滴加NaOH溶液有蓝色沉淀生成，则B可能为Cu

判断下列句子是否与短文相符。

    I'm Peter. There are four people in my family. They are my father, my mother, my grandfather and me. I'm twelve. My birthday is on 15th March. My parents are both doctors. They help people. Their birthdays are both in May. My grandfather is old. He is sixty-five. His birthday is on 9th June. He likes reading. I like reading too. I want to be a teacher in the future. I want to teach Chinese in a school.