根据规定，采购文件的保存期限为从采购结束之日起至少保存( )年。
A．3B．5C．15D．20
参考答案：C
Jack went to college last year and left his parents, ______ to return home until he achieves his goal. [ ]
A. determining not
B. not determined
C. not determining
D. determined not
患者女，41岁。头痛半年，加重10d。头部MRI显示如下图。
根据该病的影像学表现，该病可能的诊断是（）
A.海绵状血管瘤
B.发育性静脉畸形
C.AVM
D.毛细血管扩张症
E.动脉瘤
F.硬脑膜动静脉瘘
