在排水系统控制城市污水与雨水管渠为一个系统的叫做（）。
A、完全分流制排水系统
B、不完全分流制排水系统
C、合流制排水系统
D、以上都不是
参考答案：C
已知a、b互为相反数，c、d互为倒数，x=6，求2a+2b+x2+（cd）2009的值．
--- ______ Linda often ______ kites in the park in spring?
--- Yes, she often ______ kites with her friends and sometimes they have a picnic together.[ ]
A. Does, fly, flies
B. Do, fly, flies
C. Are, fly, flies
D. Is, fly, flies
