Researchers at the University of Colorado are investigating a series of indicators that A B could help themselves to predict earthquakes.

Themselves

Answer: D Test point: a reflexive pronoun. Analysis: only when the subject and object of the same person or thing, object component is available with a reflexive pronoun. Sentence as a complex sentence, the attributive clause subject indicators and themselves is the subject of the main clause Researchers it should be them. Problem-solving points; reflexives often test TOEFL exam questions. See crossed -self or -selves end of the word, should pay attention to it in the sentence was intended on the subject of whether the (action perpetrators).