once
1.下面五句意思相同:
- Once you reach land, you are safe.
- If once you reach land, you are safe.
- When once you reach land, you are safe.
- If you reach land, you are safe.
- When you reach land, you are safe.
第一句里的Once用作连接词。习惯上被它引导的从句总是很短的,不该用它引导较长的从句。如Once you reach the house at the top of the next street, you are safe里的Once改作If once好些。
2.下面两句意思不同:
- He beat me once.(他有一次打败了我。)
- He beat me for once.(他只有一次打败了我[在其他时候总是我打败他的]。)
for once可以改作for this once或this once。
3.not once是“一次也没有”,就是“永不”。例如:Not once have you done as I have asked.注意用have you,不用you have。not once or(或nor)twice是“不止一二次”,就是“多次”。
4.once and for all不及once for all普通。
5.once on a time远不及once upon a time普通。
6.指自己的事时,除了故意把它说得好像故事一样以外,一般不用once upon a time,单用once就是了。
7.once in a way偶尔前面有for。