Old people are particularly ______ members of our society. A: audible B: vulnerable C: probable D: eatable

19.Our history teacher is a very _________ person and we admire him very much. A: eatable B: knowledgeable C: selfish D: unbelievable

下面哪些主动形式可以表被动意义? A: 某些用于be动词后的形容词，如eatable, acceptable等。 B: 半系动词如感官动词后面加形容词 C: 表示某种属性或功能的动词，如read, wash,clean等 D: 有些介词结构可以表被动，如on display，under discussion等 E: 有些动词后加ing形式表被动，如require, need, deserve, be worth doing等。 F: 有些句型如sth is easy, difficult, expensive to do sth. G: 有些表示开始或结束的动词，如begin, finish等。