平津战役中，人民解放军和平解放了[ ]
A．天津
B．北平
C．长春
D．徐州
答案：B
MgO是一种酸性氧化物。
If your knowledge can be in some way __________ with my experience, we are sure to succeed.[ ]
A. joined
B. united
C. connected
D. combined
