前庭水管内容物为()
A．球囊斑
B．内淋巴液
C．椭园囊斑
D．外淋巴液
E．内淋巴囊
参考答案：B
Some people waste a lot of food ________ others haven’t enough to eat.
A．however
B．when
C．as
D．while
如何进行废热锅炉启运操作？
