Decided.( /dɪˈsaɪdɪd/ )
Definition: This refers to a person who is clear about their goal or intentions.
Synonyms: determined,pronounced,sure
Antonym: uncertain,vague,indistinct
Word Family: decisive,decision,decisively.
Word associations: determined,sure,settled.
Collocation: Decide between,decide on,decide to.
Sample sentences:
I decided to study more.
I decided that I would do well in English.
Personal sentence:I decided to improve my English since it is necessary for my studies.

Determined (/dɪˈtɜːmɪnd/)
Definition:The desire to obtain or complete something and not let anything stop you
Synonyms: Confident,decisive,firm.
Antonym: doubtful, lazy, indecisive.
Family words: determination, determined, predetermined.
Word association: firm, resolute, persistent, constant.
Collocation: determined to .
determined to have,
it was determined that.
Sample sentences:
He is a determined character,
He is someone determined with what he wants,
You feel strong, determined and ready to take on more at work.
Personal sentence: I am someone determined to get what I want.
Persistent(/pəˈsɪstənt/)

Definition: To continue doing something or trying to do something even if it is difficult or even if other people want you to stop.
Synonyms: Tenacious, determined,persevering.
Antonym: Surrendering,quitting, irresolute.
Family words: perseverance, determination
Collocation:
my persistent attemp.
Persistent concern.
Sample sentences:
His attempts to get something were persistent.
Today there is a persistent heat.
The people at Entel are very persistent with their offers.
Personal sentence:I am quite persistent when I want something like a good grade.
Understand( /ˌʌndəˈstænd/)

Definition: perceive the meaning or grasp the idea to understand what is shown.
Synonym:Think,conclude, decide.
Antonym: misunderstand, misinterpret,misconceive.
Family words:know, comprehend, grasp.
Collocation:
Understand the.
WE understand.
Understand your.
Sample sentences:
He understands the class well.
It may be difficult to understand the new classes.
Personal sentence:
It’s difficult for me to understand some new things in English, but with time I’ll be able to learn better.