题目

归纳法是学习化学的重要方法之一，如图所示正确的是为( ) A . B . C . D . 答案：D All possible means ________ , but nothing can prevent the buildings ________． [　　] A．has tried; from being pulled down B．have tried; from pulling down C．has been tried; from pulling down D．have been tried; from being pulled down