2017年年大学英语六级基础语法知识
导语：英语四六级考试中，单独考察语法的题型不多，但是语法知识点却贯穿整张试卷，这是由百分网小编为大家整理的'“大学英语六级基础语法知识”供备考使用。
情态+动词进行/完成进行时
情态动词也可以和动词进行形式或完成进行形式构成谓语：表示"应当正在……"，"想必正在……"的意思。
【例如】
why should we be sitting here doing nothing?
she might still be thinking about the question you raised.
he can’t be swimming in such weather.
at the moment she may (might) be playing with her schoolmates.
we needn’t be standing here in the rain. we might take shelter in the hut over there.
情态动词间或也可以和一个动词的完成进行形式构成谓语，表示"应当一直在……"，"想必一直在……"这类意思。
【例如】
they are sweating all over. they must have been working in the fields.
they may have been discussing the problem this morning.
she couldn’t have been swimming all day.
worth的用法
worth，worthy，worth-while都为adj. 意为"值得"。
1. worth： be worth + n. 当名词为金钱时，表示"…… 值得……"
be worth doing sth. "……某事值得被做"
The question is not worth discussing again and again.
2. worthy：be worthy of +n. 当名词为抽象名词时表示"……值得……"
be worthy to be done "某事值得被做"
The question is not worthy to be discussed againand again.
3. worth-while： be worth-while to do sth "值得做某事"
worth while： It is worth while doing sth
It is worth while sb to do sth.
典型例题
It is not ____ to discuss the question again and again.
A.worth B.worthy C.worth-while D.worth while
答案C. 由worth的用法可知，此句只适合词组be worth-while to do sth.。因此选C。
【2017年年大学英语六级基础语法知识】相关文章：