题目

—How nice the fish tastes! Could you tell me who taught you to cook it?           —To be honest, I learn it ________ watching TV. I learn to cook many dishes ______ TV. A.      By; in     B. by; on       C. in; on        D.By; on 答案：B求下列各式中的x：（1）225x2-144=0                       （2）25（x-1）2=49（3）x2=289                              （4）x2-5=0．