我们把两组邻边相等的四边形叫做“筝形”.如图,四边形是一个筝形,其中,.对角线,相交于点,,,垂足分别是,.求证. 答案:证明:在△ABD和△CBD中 ,∴≌(SSS) ……………………………4分 ∴,∴BD平分∠ABC ……………………………6分 又∵,∴ ……………………………8分We are happy to see our city developing ________ these years than before.A. very quickly B. the most quickly C. more quickly