Lexical resource error. Consider the word meaning difference between illustrious and illustrates :
Illustrious - highly distinguished; renowned; famous
Illustrates - to furnish (a book, magazine, etc.) with drawings, pictures, or other artwork intended for explanation, elucidation, or adornment.
As you can see, you had a word choice error that would impact your vocabulary score. Since you are an ESL user, your dictionary should be your best friend. Always look up the word meaning while you can to be sure you are using the correct refence. Build your vocabulary now while you are practicing because these costly errors will affect your final score.
two or more cars were prefer.
Sentence clarity problem. Your sentence structures become incorrect due to your lack of vocabulary proficiency. These are errors that should be addressed by your English language teacher through sentence building exercises. In this case it is the usage of the word "preferred" that caused the mistake.