下列多项式中，能用公式法进行因式分解的是 [ ]
A．a2﹣b2
B．a2﹣2ab﹣b2
C．a2﹣2ab+42
D．a2+ab+b2
答案：A
It ______ the year of the horse next year. [ ]
A. is going to be
B. is going to
C. will be
D. will is
胸骨左缘第二肋间闻及收缩期杂音的病是（）.
A．三尖瓣狭窄
B．主动脉瓣狭窄
C．动脉导管未闭
D．室间隔缺损
E．房间隔缺损
