1. Right answer:
Uds. estuvieron en la clase de inglés
To change this sentence from the simple present to the preterite tense, we need to change the conjugation of the verb estar. First of all, están is the conjugation of the verb estar that matches the second person singular (ustedes) in the simple present. By changing this conjugation, we have the new word estuvieron, which is the conjugation of the verb estar for the second person plural in the preterite tense. Finally:
Sentence in the simple present:
Uds. están en la clase de inglés.
Sentence in the preteirte:
Uds. estuvieron en la clase de inglés.
2. Right answer:
Mi padre puso el auricular en la mesa
The same happens in this sentence, so pone is the conjugation of the verb poner that matches the third person singular (él - masculine form) in the simple present. By changing this conjugation, we have the new word puso, which is the conjugation of the verb poner for the third person singular in the preterite tense. Finally:
Sentence in the simple present:
Mi padre pone el auricular en la mesa
Sentence in the preteirte:
Mi padre puso el auricular en la mesa