密相输送的推动力是（）。
A.两端的动压差
B.两端静压差
C.高流速的气体
D.机械能之差
参考答案：B
In the 1970s, people from around the world settled in the UK to live and work, _____ food from home which
attracted the British. [ ]
A. to bring
B. bringing
C. brought
D. bring
小儿急性肾小球肾炎的病因中最常见的相关病因是（）
A.金黄色葡萄球菌B.
B.β-溶血性链球菌
C.肺炎支原体
D.乙型肝炎病毒
E.肺炎链球菌
