5,-7.4,-3, +34 .
Mrs. Miller's and her son's____(嘴巴) are very big.
将矩形纸片ABCD按如图所示的方式折叠,得到菱形AECF.若AB=3,则BC的长为____ .
选项中能正确反映安第斯山脉的形成的是( )