(1) Clouds are like signs of weather () () What kind of weather will appear when clouds hang in the sky (). ...

Thin clouds in the sky are usually a symbol of good weather: those low and thick clouds are usually a sign of rain and snow.

3. Introduce the location and morphological characteristics of cirrus, cirrus, cumulus and cumulus in turn and their relationship with weather changes.

4. Metaphor cirrus clouds are light and white.

5. The relationship between cloud shape and weather change.

6. List numbers, make analogy, and the shape and position of cumulus clouds.

7. These two words play a restrictive role in the sentence, which shows that their language expression is rigorous and accurate in the case of "general" and "frequent", excluding special circumstances. (The above subjective questions all have the right meaning. )