Answer: First of all, you must be familiar with this sentence pattern:

It is +adj. +to do sth.

In this sentence pattern, it is the formal subject , is is the linking verb, adj. is the predicate, to do sth. is the infinitive phrase as the real subject.

The original sentence is To do sth. is +adj. In order to avoid being top-heavy, I asked it to help. For example:

It is very important to learn English well. It is very important to learn English well. <--The original sentence is: (To learn English well is very important.)

This is a simple sentence with a main table structure.

We turn it into a compound sentence:

1.1 I think that it is very important to learn English well. I think it is very important to learn English well.

That introduces an object clause. Since the conjunction "that" has no meaning and is not an element in the clause, it can be omitted:

1.2 I think it is very important to learn English well. But it is still a compound sentence.

We may also say: 2. I think (that) to learn English well is very important. (The formal subject it is not used in the thi sentence)

Think can not only be followed by a noun As an object, the clause can also be followed by a compound object (= object + object complement). The object complement can be an adjective, such as: I thought her rather clever. I thought she was quite clever.

So sentence 1 can be simplified to: I think it is very important to learn English well. This is a simple sentence.

Think is followed by a compound object, it is the formal object, and very important is the object complement. to learn English well. It’s true.

But sentence 2. cannot be so simplified. Can't say: * I think to learn English well very important.

The second sentence You must become the master of time not its servant.

What sentence pattern is this? It depends on what you base the points on. According to function, it is a declarative sentence. According to the structure, it is the main system structure in a simple sentence. (Generally based on the structure)

You must become the master of time (,) not its servant. You must become the master of time (,) not its servant.

You - subject

must become - predicate (become is a linking verb, followed by a noun as a predicate)

the master of time, predicate.

not its serant= not the time's servant is a parallel predicative, preceded by a comma to replace the coordinating conjunction and

A structure like A not B is common, treat it as a whole.

So it can also be said: the master of time not its servant The master of time, not its servant, is the expression of must become.

Judging from your second question, you need to complete the grammatical item of complementing the copula.

The typical copula is Be, but there are other copulas transformed from substantive verbs, such as look, sound, feel, turn, grow, come, go, etc.

You can’t even tell the difference between it and its? it is the nominative and object case of the personal pronoun (it), and its is its possessive meaning "its". Just like the difference between you and your.

The master of time, the master of time, uses the possessive case of of. its sevant is the possessive pronoun. It means "its servant", how could it become it servant?