Write the upper or lower couplet of the following poem.

1. Why is the canal so clear? (Because there is running water at the source)

2. Qian Fan by the shipwreck, (Wan Muchun in front of the sick tree)

Leaves fall like the waves of a waterfall (and I always watch the long river roll forward)

4. The desert is lonely and straight.

5. (The sea rises and the moon rises), and the horizon at this time is * * *.

6. Moonlight in the pine forest, (crystal stone in the stream)

7. (I don't know the true face of Lushan Mountain), I was born on this mountain.

8. (But you have broadened your horizons by 300 miles). Walk up a flight of stairs.