Most indicates nearly all of a group or amount. You use most with an uncountable noun or a plural countable noun.
Most people recover but the disease can be fatal.
Most farmers are still using the old methods.
Several usually indicates an imprecise number that is not very large, but is more than two. You use several with a plural countable noun.
Several projects had to be postponed.
I had seen her several times before.
There were several reasons for this.
all, both, and either
1.242 All includes every person or thing of a particular kind. You use all with an uncountable noun or a plural countable noun.
They believe that all prisoners should be treated the same.
Both is used to say something about two people or things of the same kind. You use both with a plural countable noun. The two people or things have usually been mentioned or are obvious from the context. Both is sometimes used to emphasize that two people or things are involved, rather than just one.
There were excellent performances from both actresses.
Denis held his cocoa in both hands.
Either is also used to talk about two things, but usually indicates that only one of the two is involved. You use either with a singular countable noun. When it is part of the subject of a clause, the verb is in the singular.
No argument could move either old gentleman from this decision.
If either parent has the disease, there is a much higher chance that the child will develop it.
Note that either can mean both of two things, especially when it is used with end and side.
They stood on either side of the bed.
each and every
1.243 You use each and every when you are talking about all the members of a group of people or things. You use each when you are thinking about the members as individuals, and every when you are making a general statement about all of them. Each and every are followed by a singular countable noun.
Each seat was covered with a white lace cover.
They would rush out to meet each visitor.
This new wealth can be seen in every village.
Every child would have milk every day.
Each applicant has five choices.
I agree with every word Peter says.
You can modify every but not each. You can say things such as Almost every chair is broken or Not every chair is broken but you cannot say Almost each chair is broken or Not each chair is broken. This is because each is slightly more precise and definite than every.
Note that each can be used when talking about two people or things, but every is only used for numbers larger than two.
little and much
1.244 If you want to emphasize that there is only a small amount of something, you use little. You use much to emphasize a large amount. Little and much are used with uncountable nouns.
Little is used only in affirmative statements. It is not used in questions or negatives.
There was little applause.
We’ve made little progress.
We have very little information.
Little is quite formal. In less formal texts, not much is more common. For example, instead of saying We’ve made little progress, you can say We haven’t made much progress.
Much is usually used in questions and negatives.
Do you watch much television?
He did not speak much English.
Very much is used only in negative statements. For example, I don’t have very much sugar means I have only a small quantity of sugar.
I haven’t given very much attention to this problem.
Much is used in affirmative statements when it is modified by an adverb such as too, so or as.
It would take too much time.
Provide as much information as you can about the property.
In more formal English, much can be used in affirmative statements without an adverb. This usage is most common with abstract nouns, particularly those relating to discussion, debate and research.
The subject of company annual accounts is generating much debate among accountants and analysts.
The team’s findings have caused much excitement among medical experts.
After much speculation, intelligence agencies now believe that he survived.
Usually, though, much is not used in affirmative statements. Instead, people generally use a lot of and, in less formal texts, lots of. For example, people would not usually say I have much work to do; instead, they would say I have a lot of work to do. For more information on a lot of, see 2.176.
certain, numerous, and various
1.245 Some other words can be indefinite determiners, such as certain, numerous, and various. You use certain, numerous and various with a plural countable noun.
Certain is used to refer to some members of a group, without specifying which ones.
We have certain ideas about what topics are suitable.
Numerous, like many, indicates a large number in an imprecise way.
I have received numerous requests for information.
Various is used to emphasize that you are referring to several different things or people.
We looked at schools in various European countries.
more, few, and less