在复平面内，复数2-i1+i对应的点位于第______象限．

She ______ for 15 years, yet she didn’t know what kind of man she ______.

A．had married; married

B．had been married; married to

C．had been married; had married

D．married; had married to

胰头癌区别于壶腹周围癌的检查所见是（）。

A.大便潜血试验（+），黄疸进行性加重

B.血管造影提示门静脉受浸润

C.PTCD显示胆管下端梗阻

D.血淀粉酶高于正常

E.大便苏丹染色阳性，显示脂肪颗粒

每个圆都只有一条直径，两条半径．______（判断对错）

我国明代朱载堉首创新法密率，即“（）”。