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A vocabulary is a set of familiar words within a person's language. A vocabulary, usually developed with age, serves as a useful and fundamental tool for communication and acquiring knowledge.

In linguistics, grammar is the set of structural rules governing the composition of clauses, phrases and words in a natural language. The term refers also to the study of such rules and this field includes phonology, morphology and syntax, often complemented by phonetics, semantics and pragmatics.

Comprehension is the ability to process text, understand its meaning, and to integrate with what the reader already knows. Fundamental skills required in efficient reading comprehension are knowing meaning of words, ability to understand meaning of a word from discourse context, ability to follow organization of passage and to identify antecedents and references in it.

An average is a single number taken as representative of a list of numbers. Different concepts of average are used in different contexts. Often "average" refers to the arithmetic mean, the sum of the numbers divided by how many numbers are being averaged.

In mathematics, a percentage is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%", or the abbreviations "pct.", "pct"; sometimes the abbreviation "pc" is also used. A percentage is a dimensionless number (pure number).

In mathematics, a ratio indicates how many times one number contains another. The numbers in a ratio may be quantities of any kind, such as counts of people or objects, or such as measurements of lengths, weights, time, etc. In most contexts, both numbers are restricted to be positive.