Punctuate and capitalize the sentence
Every generally takes singular verb.
We use is for every & each.
Every man is responsible.
Articles "A" and "AN" are used with some expressions.
For example:
Make a noise, give a warning, have a pain, have a great education etc.
"A" is used before a singular, countable noun when mentioned for the first time.
"A letter" fits because it refers to one unspecific protest letter.
Article A is used before common things, places or persons.
Article The is used before particular things, person or places.
Bitter, Bitterness : کڑواہٹ, کڑوا :
The comparative degree of bitter is bitterer
A superlative degree of bitter is bitterest.
more bitter and most bitter are the usual comparative and superlative forms
***
ND9-11-2022
Well known takes for.
Well known for something means well known for qualities.
For is a preposition here.
Hamza is well known for his benevolence.
Benevolence means خیر خوائی
Here this sentence is talking about a particular book.
We use the before a particular thing.
The is an article here.
I enjoyed reading the book you gave me.
"The environments" refers to specific natural settings already known or implied.
Use of "the" is proper when talking about general threats to particular environments.
Go by train or by a bus.
A is an article here.
Here A bus means کسی بس پر