Questions 15 to 17 are based on the
following passage. At the end of the passage, you will be given 15 seconds to
answer the questions. Now, listen to the
passage.
What could scientists do if Robert’s theory proves to be true
A．They could drive the insects away. B．They could keep the plants well-watered. C．They could make the plants grow faster. D．They could build devices to trap insects.