题目

生长旺盛的叶片，剪成5mm见方的小块，抽去叶内气体，做下列处理(如下图所示)，这4个处理中，沉入底部的叶片小块最先浮起的是（ ） A . B . C . D . 答案：C Having ________ fair attitude towards people with different ideas is ________ indication that one has been well educated A．a, an B．the, the C．/, the D．a, /