【单选题】听力原文:M: Well, that was delicious! Thanks very much indeed. . . I didn't know you were such a good cook, Brenda. W: Thank you, Richard. M: If you like, I could do the washing-up. W: No, don't bother, I...
【简答题】Diaphragm valves use a flexible and to regulate flow. The handwheel operates just like the handwheel on valve. The is attached to a device called the . The compressor pushes on a flexible diaphragm. T...