<h2>Correct answer:</h2><h3>b. Anita es menor que Marta.</h3>
Since <em>Marta is 15 years old</em> and <em>Anita is 14 years old, </em>thereforeAnita is younger than Marta. So in this sentence we use the form menor que after the conjugation of the verb ser for the third person singular in the simple present, which is es. Finally:
<em>Anita es menor que Marta</em>
Answer:
There is no correct Ud. or Uds. command for these sentences. The directions ask for the tú command.
Explanation:
Penicilina se hizo un antibiótico
ciclotron para la investigación atómica entra en funcionamiento
la liofilizacion para los alimentos
primera vacuna contra la lepra
