自然界只存在两种电荷,一种是正电荷,另一种是____ 电荷.当甲乙两个通草球出现如图所示情形时,若甲带正电,则乙带____ 电.
Our teacher us his friends. We all love him a lot.
The large house with a garden faces towards a river.
口算。
11-7=____12-7=____13-7=____
14-7=____ 15-7= ____ 16-7=____
从中国到德国选择最近航线,货轮经过海峡的先后顺序是( )