We are supposed to talk with the old _________.
A:polite
B:impolite
C:impolitely
D:politely
计算:﹣2+4=____ .
卫生间的毛巾挂钩,用胶可以牢牢粘在瓷砖墙上,这是因为分子间存在____;将50 mL的水和50 mL的酒精混合,所得液体体积小于100 mL,这是因为分子间存在____.