阀门填料更换后，装上填料压盖，用螺栓紧固，但不能压得太紧，能使（）上下活动自如即可。
A、阀座
B、阀芯
C、手轮
D、阀杆
参考答案：D
Our playground is not so tidy and beautiful as before. Students must _____ dirty things on it.
A. be stopped to throw
B. be stopped from throwing
C. stop to throw
某患者 * * 部掀红漫肿极甚，疼痛难忍，毛孔深陷，恶寒发热，3天后皮肤湿烂，变为色黑腐烂的溃面。应首先考虑是什么病
A．外吹乳痈
B．乳疽
C．乳发
D．内吹乳痈
E．非哺乳期乳痈
