有關 "No" 的問題?

1. No student is to leave the room 與 No students are to leave the room 的實質意義相同，因no student = 0 student, 而no students 也是 = 0 student. – (0 乘任何數還是等於0)
前句與後句的些微差別在於說話者的心態感知，前句說話者原本預期會有一個人(單數)會離開教室，但實際上沒人離開教室。故他說No student is to leave the room。後句說話者原本預期會有多個人(複數)會離開教室，但實際上沒人離開教室。故他說No student are to leave the room.
2. There were no letters this morning 與 There was no letter this morning 的實質意義也是相同. 前句說話者原本預期會收到多封信(複數)，但實際上沒收到一封信。故他說There were no letters this morning。後句說話者原本預期會會收到一封信(單數)，但實際上沒收到一封信。故他說There was no letter this morning.
以下為國外英文討論，你試試看，看這種文章對英語的進步也有很大幫助。
There is an obvious difference between these two:
There is no car.
There are no cars.
The first one is singular, the second one is plural. However, because
there is a negation, the result is the same: there are zero cars. So as
such, the two sentences both mean the same. They are also both
grammatical.
Another way to say the same is using any, and the correct way of
doing that (again singular and plural are correct!) would be:
There is not any car.
There aren't any cars.
Now, if we have four ways to say the same thing, which one do we
choose?
Actually, the difference between the four options is quiet small, but
there is a little bit of difference in how we feel part of the message is
stressed.
If we are talking about a single car, say a car that I have reserved at a
car rental, but they messed up my reservation, you could have a
conversation like this:
customer: Where is my car?
clerk: I'm sorry, I have no reservation for you. There is no car for you. (店員說:我本來就沒有幫你保留特定款的的ㄧ部車)
customer: well, if my reserved car isn't there, give me another one.
clerk: I'm sorry, but there isn't any car available.(店員說:沒有任何ㄧ部車是可分配給你的)
customer: You are a car rental company, and yet there are no cars? (顧客說:你是租車公司，居然沒有多部車準備著)
clerk: It has been very busy, and indeed, there aren't any cars left
here.(店員說:今天很忙，(往常是會有很多車準備著，)今天的確沒有你想要的任何一款車)
資料來源
https://ell.stackexchange.com/questions/32832/whats-the-difference-between-theres-no-car-and-there-are-no-cars?rq=1

"singular"(grammar) is of the form used in speaking or writing of one person or thing.;the singular number.What is the singular of students=student.
"plural"(grammar) n. adj. is the form of to be used with reference to more than one:-eg:-The plural of student is students.--the quality of being plural.---the state of being plural,---holding of more than one.
In determinant of agent,element,it is not one; not any; not a; to determine or deciding:-
eg:-No student is to leave the room-----singular no.
eg:-Ther's no bread left------singular no.
In determinant(adj)(n), it is determining or deciding element,factor:-
eg:-There were no letters this morning-----plural; past tense of are=were.
eg:-No two days are the same------plural in no.in present tense.
Determinant of agent, factor limited, is used to express the opposite of what is mentioned:-
eg:-She's no fool(=she's intelligent)
eg:-It was no easy matter(=it was difficult)--plural in the past tense of is=was
Note the similar use of no and none.The word "any" adv of degree, is used in negative conditional, where doubt implied.eg:-If it's any use, I'll but it.