如果一个两位数的十位数字与个位数字之和为6,那么这样的两位数的个数是( )
Last week I met my old friend Li Ming by accident but I forgot _______ him for his telephone number.
函数fx=Asinωx+φ(其中A>0,φ<π2的图象如图所示,为了得到gx=sin3x的图象,只需将fx的图象( )