Ser & estar doctor and place

Translate the sentence below into english.    pienso que nunca lo sabré. a. she doesn't believe he will ever find out. b. i believe that i'd never find out. c. she thinks that i'll never find out. d. i think that i'll never find out.

Spanish, no translator 1. translate: i have to eat. 2. translate: one must study. 3. to make a good grade, one must pay attention. para sacar una buena nota, prestar atención. 4. to make money, one must work. para ganar dinero, trabajar. 5. translate: maria has to talk.

What is the phrase decir que used to express in spanish?