用字母给下列句子排序。

A. I like my kite. It's nice.

B. Can I help you?

C. Thank you.

D. Here you are.

____ ____ ____ ____ 

细胞中的无机盐大多数以____ 形式存在，叶绿素中就含有____，血红蛋白中含有____．

阅读下列短文，从每小题的三个选项中选出最佳答案

      It is morning now. Look at the sun, it rises in the east(东方). Look at the tree, the shadow is long. It is noon now. The sun is high in the sky. It is very hot. Look at the tree. The shadow is short. It is evening now. The sun goes down in the west(西方). Look at the tree, the shadow is long again. It is night now. The moon is high in the sky. There are some stars in the sky too.

①有一个角是直角的四边形是矩形；

②一组邻边相等的平行四边形是菱形；

③一组邻边相等的矩形是正方形；

④一组对边平行且相等的四边形是平行四边形．

其中真命题的个数是（   ）