### 第1段

1 .<-NARRATOR:-> Now listen to part of a lecture on this topic in a biology class.

### 第2段

1 .<-MALE PROFESSOR:-> So, here's a good example of this.

2 .Mites are very small insect-like creatures.

3 .Mites live in tropical climates and feed on nectar and pollen in flowers.

4 .But these tropical flowers don't last long,

5 .they wilt and fall off quickly, and so the mites need to find new flowers in order to get more nectar and pollen to eat.

### 第3段

1 .But the mites can't fly,

2 .and they are so small

3 .that it'd take them a while and a lot of effort to climb down one flower,

4 .crawl to another one,

5 .and climb all the way up again.

6 .So how do they get to the next flower?

7 .Well, there's a bird,

8 .the hummingbird... hummingbirds eat the nectar from the same flowers as the mites.

9 .So when a hummingbird comes around and sticks its beak into the flowers to get the nectar out . . .

10 .the mites quickly climb onto the hummingbird.

### 第4段

1 .Well, as I mentioned, mites are pretty tiny,

2 .so the hummingbird isn't harmed in any way.

3 .And all they do is stick to the hummingbird.

4 .Since the hummingbird also goes from flower to flower for nectar, it takes the mites along.

5 .Once the hummingbird gets to the next flower,

6 .the mites climb off and eat some pollen and nectar there...

7 .on the new flower. Without the hummingbird carrying them from one flower to another,

8 .the mites would find it much more difficult getting food.