鼻咽纤维血管瘤起源于枕骨底部、蝶骨体及翼突内侧的骨膜,肿瘤由致密结缔组织、大量弹性纤维和血管组成。
参考答案:对
I think you should end it _______ it’s too late, or you may be sorry about it later.
A.after
B.when
C.until
D.before