1. By the time he realizes he has walked into a
trap,it'll be too late for him to do anything about it.
By the time he went abroad,he was fourteen.
看这两个例子就明白by the time相关的主从句都没有一定要用什么时态的规定,其实各种时态都有可能,只不过主句中完成时常见.
2. 英语表示特指的除了the之外,最常见的就是指示代词this/that/these/those了.It is said that Van Gogh succeeded in selling only one painting in his life,_______sold to his brother.这一句中,后面的同位结构非常明确,就是前面所说那幅only one painting in his life,所以用the one语气更加清楚.
3. -You' re trembling. What's happened?
-I _______out side in the cold for over an hour waiting for a bus.
A. was standing B.have been standing C.stood D. will stand
这个空其实填have stood outside应该也没有问题的,用现在完成时表示过去的动作stand对现在造成的影响 be trembling; 用过去进行时是强调当时的状态,比较形象.过去时的话,发生了,结束了,仅此而已.
4. Seeing the blind wandering through the traffic,motorist would step on their brakes at once.
这个现在分词表示的动作几乎是与主句动词同时发生的,所以用一般时态；如果分词动作特别明显地早于主句动词,一般会用完成时态.
5. Having sent several mails to apply for jobs, Susan waited for a reply, but ______ came.
我感觉nothing和none的区别很微妙.NOTHING = "no thing", referring to inanimate objects
NONE = "no one", referring to people, or animals 这是比较重要的一点.另一点我认为是none突出数量,而nothing突出没有这个事实或状态.请多看例句体会.