Both ..and.意思为两者都,肯定句;neither...nor...意思为两者都不,否定句
eg:Both my sister and I are students.(注意both..and句型,be动词要用are/were...名词要用复数)
Neither my sister nor I am student.(neither...nor句型,be动词要跟第2主语的变化而变化,名词要同单数.)
All...意为全.三者以上,肯定;None..意为全不(三者以上),否定.
already 和yet.
在句中不译.
already用在肯定句.
yet用在否定句和疑问句中.