A:4 1
B:4 2
C:4 4
D:8 2
多音字组词
难nán____ nàn____ 蔓màn____ wàn____
Jumping out of ______ airplane at ten thousand feet is quite ______ exciting experience.
若x2+x+m=(x+n)2,求m,n的值.
下列哪一项是百家争鸣局面出现的主要原因( )