为了促进儿童骨骼的正常生长发育，应给儿童补充[ ]
A．含钙丰富的食物
B．含磷丰富的食物
C．含钙和磷丰富的食物
D．含钙、磷和维生素D多的食物
答案：D
Xiao Ming is a middle school student. He is a good boy, and he studies very hard. But his family is very poor, because his mother got ill a few years ago, and his father has no job. He makes money by carrying goods(货物) for other people. Life is very hard for them, and sometimes Xiao Ming can’t afford(负担得起) the school things.
When his teacher knew this, she called on her students to raise money for him. She asked them to bring their saving-money to Xiao Ming and help him. All the students are kind and friendly. They are very glad to do it. Xiao Ming is so thankful that he studies harder than before.
根据短文内容，判断正(T)误(F)。
小题1:Xiao Ming is a good middle school girl.
小题2:His father lost his job.
小题3:His teacher called on his classmates to raise money for him.
小题4:He can afford the school things easily.
小题5:All of the students are very glad to help Xiao Ming.
在氧化还原滴定中，往往选择强氧化剂作滴定剂，使得两电对的条件电位之差大于0.4V，反应就能定量进行。( )
