题目

两块底面平整.干净的铅柱压紧后会粘在一起，需要一定的外力才能将它们拉开，这一个现象表明；烤熟的地瓜香气扑鼻，该现象表明． 答案：【1】分子之间存在引力【2】分子在不停的做无规则运动– It’s difficult for the village children to cross the river to get to school.– We think a bridge ________ over the river.A．was builtB．should be builtC．has been builtD．is being built