已知正方形的面积是9a2+12ab+4b2（a＞0，b＞0），则该正方形的边长是

Great changes____  in the city, and  a  lot offactories____.   [ ]

A. have been taken place;have been set up   

B. have taken place; have been set up    

C. have taken place; have set up    

D. were taken place; were set up

在学习与教学的要素中，学习的主体因素是（）。

专责监护人的基本条件？

退赤散2功效与作用

静脉回流障碍，出现肢体严重水肿，皮肤发绀和肤温下降等表现的时间是

A．6～8小时内

B．8～12小时内

C．4～6小时内

D．12～24小时内

E．24～36小时内