Whats an example of a spell changer preterite verb in spanish?

Can somebody me out with this spanish question? completa la oración con la voz pasiva con se. used cars for sale. carros usados. (the answer is not usa los or venta de)

Question 1 (fill-in-the-blank worth 1 points) fill the blank with the preterite tense of the verb in parentheses. yo a leer el libro ayer. (empezar) answer for blank 1: question 2 (fill-in-the-blank worth 1 points) fill the blank with the preterite tense of the verb in parentheses. ellos a trabajar. (empezar) answer for blank 1: question 3 (fill-in-the-blank worth 1 points) change this verb from the present tense to the preterite tense. yo empiezo answer for blank 1: question 4 (fill-in-the-blank worth 1 points) fill the blank with the preterite tense of the verb in parentheses. yo buena nota. (sacar) answer for blank 1: question 5 (fill-in-the-blank worth 1 points) change this verb from the present tense to the preterite tense. yo busco answer for blank 1:

Fill in the blanks of the conversation of the correct form of the verb ser: luis y yo . a luis le gusta comer mucha carne. cree que la sabrosa. yo creo que los pescados y la carne . ¿y tú persona que come verduras o te gusta más comer carne? ¿crees que la o que ?