A:②④
B:②③
C:①②
D:①③④
冬天里,户外装有水的水缸常会出现破裂,这是因为水缸里的水结成冰后,其体积____ ,密度____ (两个选填“变大”、“变小”或“不变”)
—There will be more and more robots going into people's homes.
— . We might be able to leave all the chores to them.
读俄罗斯矿产资源、工业区分布及铁路交通图,分析回答问题。