Answer:
1. conocieron; se conocieron
2. se saludaron; saludó
3. ayudaron; se ayudaron
4. vieron; se vieron
Step-by-step explanation:
The aim of the exercise is for you to practice verb conjugation in different verb tenses, using a comparing of the verbs conjugated alone and the verbs conjugated with se that inffers that the subjects are all involved in the action and object of the sentence.
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Here is the translation of the complete sentences:
(know)
Ricardo and Juan met Cristina last year.
The Gonzalez met (each other) on a trip through Europe.
(greet)
The boys greeted (each other) when they arrived at the restaurant.
The waitress greeted the boys when she brought them the menu.
(help)
The nurses helped the patient to get up.
The children helped (each other) to finish the task earlier.
(watch)
The mechanics watched the broken cars.
The teacher and the students watched (each other) for the first time in class.