____ your grandpa ____ ____?
如图,在△ABC中,AB=AC,D、E在BC上,BD=CE,AF⊥BC于F,则图中全等三角形的对数为( )
—____the Smiths____(decide) to go to China for their holiday?
—Yes.they have.
第二次工业革命影响最大的成就是( )