题目

---- What about playing football this afternoon, Sam? ---- I would rather ______ at home than ______ football. It’s too hot outside.      A. stay, play        B. stay, playing         C. to stay, to play         D. to stay, playing 答案： A如图，已知菱形ABCD的边长为2，∠DAB=60°，E、F分别是AD、CD上的两个动点，且满足AE+CF=2．连接BD．（1）图中有几对三角三全等？试选取一对全等的三角形给予证明；（2）判断△BEF的形状，并说明理由．（3）当△BEF的面积取得最小值时，试判断此时EF与BD的位置关系．