河流改道可引起自然地理区位的变更,这是区位的()
A.综合性
B.确定性
C.层次性
D.历史性
参考答案:D
面神经经过鼓室的部位的()
A.上壁
B.下壁
C.后壁
D.内壁
E.内上壁与后壁
— Do you know ?
— In the 6th century.[ ]
A. who is the abacus invented
B. when the abacus is invented
C. when was the abacus invented
D. when the abacus was invented