题目

Feeling a little blue? Here are ten fast and easy waysto smile． 1．Play outside Leave your apartment and to outside．Sun and fresh air are good for you． 2．Exercise When _______ , your brain releases a chemical calledendorphins．This chemical makes you feel happier．That is just another reason why exercise is good for you． 3．Have a Heart-to-Heart chat If something is bothering you, it is a good idea totalk about it．Call a friend or relative．A good chat is great feel better fast． 4．Play Pop Music Westlife, Backstreet Boys, S．H．E…who doesn’t like a little mindlesspop如图，已知梯形ABCD中，AD∥BC，BD是对角线．添加下列条件之一：①AB=DC；②BD平分∠ABC；③∠ABC=∠C；④∠A+∠C=180°，能推得梯形ABCD是等腰梯形的是________（填编号）．