下图中描述细胞分化过程的是( )
A.
B.
C.
D.
答案:D
Shy people often avoid situations _____ require close contact with other people.[ ]
A. that
B. what
C. when
D. where
()摄入量过多也会导致肥胖。
A.无机盐
B.蛋白质
C.维生素
D.碳水化合物