DSS按照模型建立和适用的特点可以分为通用模型库、专用模型库和（）
A、规划模型库
B、分析模型库
C、综合模型库
D、智能模型库
参考答案：D
____ around the fire, the tourists danced with the local people. [ ]
A. Gather
B. To gather
C. Gathering
D. To be gathering
The more one is ______ the English－speaking environment，the better he or she will learn the language.
A．exposed to
B．filled in
C．caught on
D．kept up
