Asslamualaikum,
I hope all are fine. The basic things in Grammar in which most of the students are confused, let me illustrate them.
SENTENCE: A group of words which has subject and predicate and gives clear and complete sense is called sentence.
Ex: He is a student. (Here we have subject (He) and predicate (is a student). Sentence has five kinds.
1)Declarative sentence: A sentence that makes a simple statement is called declarative or assertive clause.
Ex: Aslam plays cricket.
He does not play football.
2)Interrogative sentence: It is as clear as crystal that a sentence which makes an interrogative statement.
Ex: Does she oxidize the reagent?
3)Optative sentence: A sentence in which we express wish, pray or desire.
Ex: May you pass the css!
May God bless you!
4)Imperative sentence: A sentence which contains order, request, proposal, suggestion, command etc.
Ex: Shut the door.
Come on time.
5)Exclamatory sentence: A sentence in which we express sudden and strong feelings of happiness, sorrow and joy.
Ex: Alas! He died.
Hurrah! We have won the match.
CLAUSE: A group of words that has a subject and predicate and sometimes give clear and complete sense and sometimes does not.
Ex: They are playing football. (This clause gives clear and complete sense by itself.
Ex: If he works hard. (This sentence does not give clear and complete sense by itself it needs explanation.
We can classify the clauses into two kinds:
1)Independent clause.
Dependent clause
To be continued.........

Dependent clause: A group of words that has a subject and predicate and does not give clear and complete sense by itself but need the help of other clause.
A question arises that " what is the difference b/w dependent clause and phrase if both does not give clear and complet sens?
The answer is that " phrase does not have subject and predicate while the dependant clause have both of these.
Ex: If she works hard, ( It is a dependant clause because it has subject and predicate).
Ex: In the evening ( It is an example of phrase, it is with out subject and predicate).
The dependent clause more than 9 kinds.
1) Adjective or relative clause:
A group of words that has a subject and predicate and works as an adjective. These clauses modify the nouns and pronouns of independent clause.