引起肺炎球菌肺炎低氧血症的原因是
A．V/Q＜0.8B．支气管痉挛C．高热D．痰液阻塞气道E．V/Q＞0.8
参考答案：A
已知⊙O中，OC⊥弦AB于C，AB=8，OC=3，则⊙O的半径长等于______．
Many people claimed ________ the violent attack.
A．seeing
B．to see
C．have seen
D．to have seen
