无论是种类还是数量, 动物在整个动物界都占绝对优势。
无脊椎
--What are your school ________, Jack?
-- Well, at school we have to wear school uniforms.
A.subjects
B.uniforms
C.classes
D.rules
斜轴式轴向柱塞泵改变排油方向是靠改变()。
A.转向
B.缸体偏摆方向
C.斜盘倾斜方向
D.浮动环偏心方向