题目

It is said that tea can improve creative power of the literary (文学的 ) artists in ancient China. According to Lu Yu’sTea Classics , tea—drinking in China can be traced back (追溯 ) to the Zhou Dynasty — tea was discovered by Shen Nong and became popular as a drink in the State of Lu because of Zhou Gong. Tea—drinking in China has a history of four thousand years. As the legend (传说 ) has it, Shen Nong tasted hundreds of wild plants to see which were poisonous , in order to prevent people from eating the poisonous plants. It is said that he was once poisoned but was saved 如图，在四边形ABCD中，AD=BC=12，AB=CD，BD=15，点E从D点出发，以每秒4个单位的速度沿D→A→D匀速移动，点F从点C出发，以每秒1个单位的速度沿CB向点B作匀速移动，点G从点B出发沿BD向点D匀速移动，三个点同时出发，当有一个点到达终点时，其余两点也随之停止运动，假设移动时间为t秒．（1）试说明：AD∥BC；（2）在移动过程中，小明发现有△DEG与△BFG全等的情况出现，请你探究这样的情况会出现几次？并分别求出此时的移动时间t和G点的移动距离．