题目

_______ to sunlight for too much time will do harm to your skin. A . Exposed B . Having exposed C . After being exposed D . Being exposed 答案：D如图，?ABCD中，∠DBC=45°，高线DE、BF交于点H，BF、AD的延长线交于点G；联结AH．（1）求证：BH=AB；（2）求证：AH•BG=AG•BD．