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"Past continuous" is a noun which is often translated as "el pasado continuo", and "yesterday" is an adverb which is often translated as "ayer". Learn more about the difference between "past continuous" and "yesterday" below.
past continuous( 
pahst
kuhn
-
tihn
-
yu
-
uhs
)A noun is a word referring to a person, animal, place, thing, feeling, or idea (e.g., man, dog, house).
1. (grammar)
a. el pasado continuo (M)
(m) means that a noun is masculine. Spanish nouns have a gender, which is either feminine (like la mujer or la luna) or masculine (like el hombre or el sol).
In English, the past continuous is formed through the combination the past tense of the auxiliary verb "to be" and the "-ing" form of the main verb.En inglés, se forma el pasado continuo por combinar el pasado del verbo auxiliar "to be" y la forma "-ing" del verb principal.
yesterday(
yehs
-
tuhr
-
dey
)An adverb is a word that describes a verb, an adjective, or other adverbs (e.g., to run quickly, very tired).
An adjective is a word that describes a noun (e.g., the big dog).
a. ayer 
We began our yoga lessons yesterday morning.Ayer por la mañana empezamos las clases de yoga.
A noun is a word referring to a person, animal, place, thing, feeling, or idea (e.g., man, dog, house).