正十边形的每个外角都等于( )
A:18°
B:36°
C:45°
D:60°
浮游动物、藻类、贝类、虾、鱼、微生物等为某湖泊中生活的全部生物,他们统称为( )
鲫鱼、虾、蚌、蟹都生活在水中,若将它们分成两类,其依据是( )
A. It's a naughty bird.
B. She is a cute girl.
C. The boy is very clever.
D. It's a cute elephant.
E. The teacher is very nice.