题目

Last summer holiday, I went back to my hometown, ________ the neighbours and the house ________ I used to be familiar with were gone.A. only finding; which            B. only to find; thatC. to find; whom                D. found; that   答案：B如图，△ABC中，∠C=90°，点G是线段AC上的一动点（点G不与A、C重合），以AG为直径的⊙O交AB于点D，直线EF垂直平分BD，垂足为F，EF交BC于点E，连结DE．（1）求证：DE是⊙O的切线；（2）若cosA=12，AB=83，AG=23，求BE的长；（3）若cosA=12，AB=83，直接写出线段BE的取值范围．