I wonder who that man is.
¿Quién será ese hombre?
Cisneros (observing them curiously). I wonder what's going on?
Cisneros (observándolos con curiosidad). ¿Qué pasará?
—NUÑEZ DE ARCE.
This form is used when the English sentence would make complete sense without wonder.
104. In English the one has three translations. When used in contrast with the other, it is rendered el uno. Before the relative who or that it is el. In adjective phrases such as the new one, the old one, etc., the word one is omitted.
Both boys were busy. The one was helping his mother, the other, his father.
Ambos muchachos estaban ocupados. El uno ayudaba a su madre, el otro a su padre.
You are not going from my house. They are the ones that are going.