【单选题】The cells of the body have varied and essential roles. Skin cells protect the whole body; red blood cells carry oxygen; and bone cells build the skeleton. Cells multiply fast when a person is growing,...
【单选题】The human body is incredibly __________. When you donate a pint of blood, you lose about 3.5 trillion red blood cells, but your body quickly replaces them.
【单选题】The cells of the body have varied and essential roles. Skin cells protect the whole body; red blood cells carry oxygen; and bone cells build the skeleton. Cells multiply fast when a person is growing,...