A:哺乳动物血液中Ca+含量太低会抽搐
B:Fe2+是合成血红蛋白必需的成分
C:微量元素Mg是合成叶绿素必需的
D:细胞中的无机盐大多数以离子形式存在
Name
Li Mei
Age
13
Study at
No. 1 Middle School, Class 8, Grade 7
School
not very big, trees, flowers
a school library, a reading room……
Teachers
kind ……
After-school activities
play tennis, swim……
My school
下列有关生物体结构层次的说法,正确的是( )
读南半球某区域经纬网图,回答1—2题。