— Excuse me, could you please turn down the music a little? It's too loud.
—___.
A:Oh, it's my honor to do so
B:Never mind. I like music
C:Sorry. I didn't know your were studying
D:Thank you. It's kind of you
如图,将矩形ABCD密铺在长为4cm.宽为2cm的矩形纸片右侧,若组成的新矩形与原矩形(图中阴影部分)相似,则AB=( )cm.