有关聚落的叙述,正确的是[ ]
A.聚落是指只有三家五户的小村落
B.人类先有城市聚落,后有乡村聚落
C.城市是以非农业人口为主的聚落
D.聚落是指人们居住、生活、休息的场所
答案:D
We found that this pair of sun-glasses couldn't the sun. [ ]
A. keep in
B. keep out
C. keep away
辨认如何分类?