合并同类项：     

（1）-5yx²+4xy²-2xy+6x²y+2xy+5；

（2）2（x-2y）²-7（x-2y）³+3（2y-x）²-（2y-x）³；    

（3）3a^m-4a^m-1-5a^m+4a^m-1-3（m为大于1的整数）。

The ancient penguin was     modern ones and it was good at swimming but couldn’t fly.

A．as large as twice

B．larger than twice

C．twice the size of

D．twice as larger as