por un tiempo, pero despues de poco tiempo (acostarse) y (dormirse) porque no es un libro muy bueno

Last one for it’s in english but it’s kinda tricky! i’m not sure if it’s b, so can someone . i’ll make brainliest

When could you attach the direct object pronoun to an infinitive verb? a: when an infinitive verb follows a conjugated verb. b: when an infinitive verb ends in a question. c: when a stem-changing verb ends in a question. d: when a stem-changing verb follows a conjugated verb.

19. fill in the blank with the correct conjugation of the verb in parentheses. (estudiar) en la biblioteca