List some sentences with explanations.

Stone arch bridges can be seen almost everywhere in China. These bridges vary in size and shape, and many of them are amazing masterpieces. The most famous ones are Zhao Zhouqiao in Zhao County, Hebei Province and Lugou Bridge in Fengtai District, Beijing.

2. Curves are opportunities. People who know how to grasp opportunities and curves will eventually surpass those who don't. 17 and 18 centuries, with the discovery of America by Columbus, Magellan's voyage around the world and the ignition of the steam engine, the human world has undergone tremendous changes and turning points, from economic production mode to political system to social and cultural thoughts.

The stars in the sky are like gems.

What you see is a crystal ball with alternating blue and white lines, surrounded by a thin layer of water blue "tulle".

5. The bridge opening of the stone arch bridge is curved, just like a rainbow.

6. The earth, the mother of mankind and the cradle of life, is so beautiful, spectacular and amiable.

7. The rain in spring is delicate and gentle, while the rain in summer is rough and warm.

8. As for white flowers, it is because there is no pigment in the cell fluid. Some white flowers, such as chrysanthemums, are reddish before withering, indicating that they also contain a small amount of anthocyanins.

9. It is a planet with a radius of only over 63 million kilometers. In the starry universe, the earth is like a boat.

10 However, compared with the vast universe, the earth is small.

1 1, the halo can predict the weather. For example, in Xinjiang, fainting means rain.

12. Take mineral resources as an example. It is not given by God, but formed by geological changes over millions or even hundreds of millions of years.

13, yes, scientists have put forward many ideas, for example, establishing an immigration base on Mars or the moon.

14. Scientists have proved that there is no second planet suitable for human habitation at least within 40 trillion kilometers centered on the earth.

15. However, if it is exploited without restraint, it will accelerate the depletion of mineral resources on the earth.