钢管抽芯法不仅可以留设直线孔道，亦可留设曲线孔道，胶管弹性好，便于弯曲。( )
参考答案：错
—People in Southwest China have never experienced _____ natural disaster．
—Exactly．Let's do our bit to help them．
A．a more severe
B．the most severe
C．the more severe
D．a most severe
尖晶石的典型包裹体为八面体负晶.
