Do you think animals can see colors? Scientist(科学家) think that many animals cannot see colors. The world is black and white to them. Scientists want to find out if dogs can see colors. When the scientists give the dogs food, they show them a certain(一定的) color every time. The dogs get ready to eat when they see this color. The scientists then show the dogs another color. Again the dogs get ready to eat. The colors are not all the same to monkeys. For example, if we put food in a red box, and do this every day, a monkey will always go to the red box to get food. If we put food in a blue box, the monkey won't go to eat it.

A: Bob, if(如果) I say ", Bob", you say…

B: Hello!

A: If I say "Good morning, Bob", you say…

B: Good ! 

A: How  you, Bob?

B: I'm fine, .

A: What's this  English?

B: It's a .

A: Please  it.

B: K-E-Y.

A: What  is it?

B: It's brown.

A: Yellow and(和) red is…

B: Er…

A: It's the color of the orange.

B: Now I ! It's orange.

A: So English isn't difficult(困难的). You  speak(说) English well.

—         is an egg.

  the cup?

  .