中印边境争议区、中日东海争议区面积有多少平方公里?双方各自的主张是什么?我国在南沙海区占有几个岛屿和礁盘?是哪几个?
参考答案:
12.55万、20多万、7个
两个大小不同的绝缘金属圆环如右图叠放在一起,小圆环有一半面积在大圆环内,当大圆环通上顺时针方向电流的瞬间,小圆环中感应电流的方向是( )
A.顺时针方向
B.逆时针方向
C.左半圆顺时针,右半圆逆时针
D.无感应电流
________, Jack can never catch up with Tom in the study of English. [ ]
A. However he tries hard
B. No matter how hard he tries
C. No matter how he tries hard
D. As hard he tries