原发性三叉神经痛的病因
A．急性上颌窦炎B．急性牙周炎C．鼻咽癌D．三叉神经疱疹病毒感染E．尚不清楚
参考答案：E
______ several hypotheses have been advanced for the disappearance of the dinosaur, no conclusive evidence supports any of them.
A．Despite
B．In spite of
C．Although
D．In spite of the fact
严格地讲景深范围是可以根据拍摄的（）
A.时间
B.地点
C.方位
D.具体情形
