Main clauses are ... well, main!
The subordinate ones are:
1. The Direct Object Clause
2. The Indirect Object Cl
3. The Subject Cl
4. The Predicative Clause
5. the Relative Clauses
6. The Adverbial Clause of Time
7. The Adverbial Clause of Place
8. The Adverbial Clause of Manner (plus The Adverbial Clause of Comparison)
9. The Adv Clause of Reason
10. The Adv Cl of Condition (or The If Clause)
11. The Adv Cl of Purpose
12. The Adv Cl of Result
13. The Adv Cl of Concession
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The types of clauses and their classification differ from grammar school to grammar school (and they change with ages), so they may have a different name in your country, NOW.
Adverbial subordinate clauses, adjectival subordinate clauses, and nominal subordinate clauses.
simple sentence
This is called a compound complex sentence. The main clauses are usually connected by a conjunction. The subordinate clause is connected to a main clause by an adverb.
the subordinate noun comes before the verb in the main clauses
One false statement about subordinate clauses is that they always function as independent sentences on their own. Another false statement is that they are always placed at the beginning of a sentence. Subordinate clauses can also come after the main clause in a sentence.
A simple sentence.
Some examples of subordinate clauses include adverbial clauses (e.g. "because she was tired"), relative clauses (e.g. "who lives next door"), and noun clauses (e.g. "what you said"). Subordinate clauses cannot stand alone as complete sentences because they rely on the main clause for context and meaning.
No... Subordinate conjunctions (i.e. if, because, although, while, when, et cetera) begin subordinate clauses, at least when those subordinate clauses function as adverbs...
These are called compound clauses. An example: [I went to the shop] and [I bought a loaf of bread].
No, "fortunately" is an adverb, not a subordinate conjunction. It is used to express a positive outcome or circumstance. Subordinate conjunctions connect dependent clauses to independent clauses in a sentence.
A subordinate clause modifies a word, a phrase, or a clause within the sentence, just as single-word adjectives and adverbs do. Adjective clauses follow a relative pronoun (who, that, which) and do not have a separate subject. Adverb clauses follow a conjunction and have a noun as the subject.
It is no kind of conjunction. The word during is a preposition.