1.When ___ ,ice change into water.
A.to heat B.heating C.heated D.they are heated.
我分析的是：应该是冰被加热,所以排除AB D项为什么不对我不知道 但是我觉得是分词作状语（是不是条件状语）所以就选C 另外再问下如果把B项改为 being heated是不是也是对的?
答：when heated 在这里=when it is heated,ice为不可数名词,不能用they来代替.
When being heated =when it is being heated,强调在加热的过程中,与现实情况不符,因为
2.___ his telephone number,she had some difficulty getting in touch with Bill.冰变水有一定的延缓.用一般现在时,只表示被动,不表示进行,是一客观的现象.
A.Not knowing B.Knowing not C.Not having known D.Having not known
这题因为not的位置错了 一下就排除BD 答案是A 但是我感觉C也对啊 也可以理解为know表示的动作在主句动作之前所以用完成时啊?
答：know与get to know不同,是一心理活动,not knowing sth.是一种状态,不是一个动作.这个状态是伴随主句的动作同时发生的.have known sth.一般与一段时间连用,表示“认识(某人）或知道某事,已经有多久了.
此题句相当于：Becasue she didn't know his phone number,she had some difficulty getting in touch with Bill.由于她不知道他的电话号码,她与比尔的联系遇到一些困难.
