A:171
B:17.1
C:16.1
D:1.71
— What a sunny day!
— Yes. You'd better take a sun umbrella to protect yourself _______ the sunshine.
“橘生淮南则为橘,橘生淮北则为枳”,造成这一差异的最主要原因是( )
读可持续发展复合系统示意图(下图),图中①、②、③、④号码的含义分别是( )