Science is full of wonders, and even the annual rings have been asked by universities.

Tree rings record the age of trees. Each annual ring is a year with different thickness. Even the growth rate of trees in a year will leave traces in the annual rings. Bright lines indicate rapid and vigorous growth in rainy spring, while dark lines indicate slow growth in summer. Scientists use tree rings as weather maps for the past few years. The broad annual rings tell people that the growing conditions at that time were superior ―― there was plenty of sunshine and water. The narrow rings marked the drought that year. Narrow rings in the middle can indicate that other trees cover it and take away sunlight or water. An inclined tree may be pushed by competing roots and cannot grow upright, but it will grow more wood on the other side to prevent toppling. This is also reflected in the width of the annual rings. If a tree is damaged in a forest fire in a certain year, the tree rings will show how its subsequent growth bypasses the scar.

The American Daily News once commented: "Sagan is a scientist. He has three eyes. One eye explores the starry sky, one eye explores history, and the third eye, that is, his thinking, explores the real society ... "To tell the truth, the progress of human civilization needs more scientists with three eyes like Sagan!

My backyard is a hundred flowers garden. Flowers bloom all year round, dotted with my warm home. Among the flowers, there are gorgeous roses, shy and fragrant roses … but cactus is my favorite.

The cactus is shaped like a grotesque big hand, trying to open it. It looks really ugly. A yellow-green dress is covered with small thorns. As long as your fingers are in close contact with it, even if you touch it gently, you will definitely prick it. If it is serious, there will be blood stains. Perhaps this is why "cactus" got its name.

Although the cactus is ugly, it is very drought-tolerant. My mother told me, "It can live for seven or eight days without drinking water." I didn't believe it at first, so I gave it a try. I haven't watered it for several days, but it's still as moist as alive. From then on, I like cactus more.

Cactus is not only drought-tolerant, but also extremely vital. Even if one or two branches are broken, it will not affect its growth. If you are also interested in raising, it is very simple. As long as you insert the broken branch into the soil, it can still sprout, grow and bloom. Especially in winter, cactus is not afraid of cold. When the north wind roars, it is still dressed in green and stands proudly in the wind, just like a soldier standing on the border.

Cactus is a treasure Both stem and liquid can be used medicinally. I remember the year before last, I got mumps, and taking medicine and injections didn't work. Later, I heard that cactus can cool down and reduce swelling, so my mother scraped off the thorns and peeled off the skin, and then rammed the cactus stem and stuck it on my parotid gland, suddenly feeling cool. In less than two days, my illness was cured. How noble cactus is to sacrifice itself and others!

I think: a man should be like a cactus, willing to be ordinary, not afraid of difficulties, and willing to give everything to the people.