ChoosE thE CorrECt lEttEr FromA-
D、AnD writE it in BoxEs on yourAnswEr shEEt.
thE mAin Aim oF thE writEr is to
A、point out thE EConomiC BEnEFits oF tourism.
B、outlinE thE impACt oF tourism on thE EnvironmEnt.
C、introDuCE thE ConCEpt oF ECo-tourism.
D、ExplAin thE origins oF ECo-tourism.