题目

27. Great changes _______in our city in the past twenty years. A. have been taken place                      B. have taken place C. took place                                     D. were taken place 答案：B往浅绿色的Fe（NO3）2溶液中，逐滴加入稀盐酸时，溶液的颜色变化应该是 [     ]A.颜色变浅             B.逐渐变红色        C.没有改变              D.变棕黄色