已知am=3，a2m+n=5，求a2n的值．
a2n=a2（2m+n）-4m
=（a2m+n）2÷（am）4
=52÷34
=2581．
This story made me _____ my past. [ ]
A. think of
B. thought of
C. to think of
D. think over
产后2小时内极易发生严重并发症的是（）
A.产后出血
B.尿潴留
C.产后心力衰竭
D.子痫
E.产妇精神抑郁
