下列哪种补体低下可作为SLE活动的指标之一（）
A.C3
B.C2
C.C4
D.C6
E.CH50
参考答案：A
So well _____ in 2009 that the world has agreed that it was the year of China. [ ]
A. did China perform
B. China has performed
C. was China performed
D. China is performing
冻结凿井所需要的钻孔包括）（）孔。
A.冻结孔
B.水文观测孔
C.测温孔
