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问题 单项选择题 B1型题

开窍于鼻的是（）

A.心

B.肺

C.脾

D.肝

E.肾

答案

参考答案：B

选择题
已知椭圆
x2
a2
+
y2
b2
=1的左、右焦点分别为F1、F2，点P为椭圆上一点，且∠PF1F2=30°，∠PF2F1=60°，则椭圆的离心率为（　　）
A．
3
2
B．
3
3
C．
2
-1		D．
3
-1
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选择题

— Tom is never late for work. Why is he absent today?

— Something _____ to him. [ ]

A. must happen

B. should have happened

C. could have happened

D. must have happened

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