What will the city of the future look like? No one knows for sure, and making小题1:______(predict) is a risky business. But one thing is certain-they are going to get bigger before they get smaller. In the future, care for the environment will become very important 小题2:_______earth’s natural resources run out. We will use lots of小题3:_______(recycle) materials, such as plastic, steel, glass, wood and paper, and we will waste fewer natural小题4:_______.We will also have to rely more小题5: _______ alternative energy, such as solar and wind power. All this seems certain, but there are plenty of things about city life in the future 小题6: _______ are not certain.

531系统菜单特点较老系统有（）变化？

A.全条线体系规范

B.引导式查阅路径

C.定制化个性展示

D.一步式辅助定位