下列多项式（1）a²+b²；（2）a²﹣ab+b²；（3）（x²+y²）²﹣x²y²；（4）x²﹣9；（5）2x²+8xy+8y²，其中能用公式法分解因式的个数有[      ]

A．2个

B．3个

C．4个

D．5个

It is none of your business          other people think about you. Believe yourself.

A．which

B．what

C．how

D．when