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"It is hot" is a phrase which is often translated as "hace calor", and "in the summer" is an adverb which is often translated as "en verano". Learn more about the difference between "it is hot" and "in the summer" below.
it is hot()
A phrase is a group of words commonly used together (e.g., once upon a time).
1. (weather)
in the summer()
An adverb is a word that describes a verb, an adjective, or other adverbs (e.g., to run quickly, very tired).