题干
The violent disturbances in Bangkok had progressed to a point ________ the police had to drive away the protestants with tear gas．
A：from which
B：that
C：where
D：what
答案(点此获取答案解析）
C
对应的复数是2＋i，向量 
对应的复数是－1－3i，则向量 
对应的复数为( )
p或q”是真命题，而“p且q”是假命题，则a的取值范围是