Imperfect Tense. They decided to go for a walk while the food cooled off. (decidir/ponerse)
Ellos "_____" ir a caminar mientras la comida "__" "_____" fría.
Answer : Ellos "decidían" ir a caminar mientras la comida "se" "ponía" fría.
Explanation : The subject in the first sentence is "Ellos", that is third plural person, so the verb "decidir" must be conjugated in the third plural person in the imperfect tense. "Ellos decidían". The subject of the subordinate sentence is "la comida", that is third singular person, so the verb "ponerse" has to be conjugated in the first singular person in the imperfect tense. "se ponía". The imperfect tense is used when actions happen at the same time in the past without specifying whether they have finished or not.
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