下列哪项不是骨折后长期卧床的并发症（）。
A.创伤性关节炎
B.坠积性肺炎
C.褥疮
D.尿路感染
E.尿路结石
参考答案：A
一个具有n个顶点的有向完全图的弧数是_______。
People at the party worried about him, because no one was aware（）he had gone.
A.of where
B.of the place where
C.where
D.the place
