在光学显微镜下观察一滴湛江北桥河水，发现有一些能运动的绿色小颗粒，判断它们是生物的依据是[ ]
A.呈球形
B.有细胞结构
C.体积微小
D.呈绿色
答案：B
If I _______ what the teacher says, I'll go and ask him for help. [ ]
A. won't understand
B. am not understand
C. doesn't understand
D. don't understand
下列关于马斯洛的需要层次理论中，发挥个人潜能，实现个人理想的是( )。
A．生理需要
B．安全需要
C．尊重的需要
D．自我实现的需要
