受理业务时，要积极主动，热情周到。解答疑难问题要耐心细致、准确详尽。实行“首问负责制”。
参考答案：对
论述膨胀干燥机低速运转时间为何不能太长？
—Where’s Li Hua?
—Look! He ____ tennis on the playground.
A．plays
B．played
C．playing
D．is playing
