投诉率呈（）趋势，表示卷烟企业的服务质量处于很不稳定状况，时好时坏。
A、下降
B、平稳
C、上升
D、波浪状
参考答案：D
If you get pimples, you should _____. [ ]
A. drink lots of water
B. take more medicine every day
C. call 120 at once
D. feel shy and sad
My mother often _____ me ____ housework on Sunday.
A. make… do B. makes …does C. makes …do
