小儿上呼吸道感染病初可有持续性脐周疼痛，考虑其主要原因是（）
A. 腹膜炎
B. 肠梗阻
C. 肠系膜淋巴结炎
D. 阑尾炎
E. 肠套叠
查看答案
籽棉的清理是利用各种清理设备（）中所含杂质的工序的总称。
In astern towing，a tow span，also called the tow bar or towing arch，is used to（）.
A. insure that the hawser leads directly aft as it passes over the stern of the towing vessel
B. increase the stability of the towing vessel by raising the hawser off the deck
C. reduce chafing of the towing hawser
D. prevent fouling of the hawser on deck gear located on the stern of the towing vessel
彩色电视机中，高频调谐器输出为中频图信号（）和伴音信号（）。
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