Sandstorm is a bad weather phenomenon caused by land desertification, which causes great harm to human survival. When sandstorm occurs, the visibility is only tens of meters or even several meters, and the sky turns yellow and dark A. Only the light with shorter wavelength can reach the ground. B. only the light with longer wavelength can reach the ground. C. only the light with higher frequency can reach the ground. D. only the light with lower frequency can reach the ground

Wave with shorter wavelength is easily blocked by obstacles and cannot reach the ground. Light with longer wavelength is more likely to diffract and reach the ground through the gap between sand and dust, so error a and error B are correct. Light with longer wavelength has lower frequency, so light with lower frequency can reach the ground, so error C and error D are correct

What is the impact of desertification on human beings

Devour mankind!

Why is land desertification aggravating

Land desertification desert is the product of arid climate. There were deserts on the earth long before the appearance of human beings. However, there is no insurmountable boundary between the desolate desert and the plump grassland. With water, lush plants can grow on the desert and become a green continent full of vitality. Without water and plants, the green land can grow up, In order to get more food, no matter what the climate and land conditions are, people open up wasteland and overgraze; in order to solve the problem of fuel, they cut down trees and cut grass wantonly, no matter what the consequences are, The strong wind erodes the surface soil, the sand is more and more, and the sand dunes develop slowly. This makes the arable land become the desertification land which is not suitable for grazing and farming. Land desertification is a sign of environmental degradation and a positive feedback process of environmental instability. If no fundamental measures are taken, the process of soil wind erosion and desertification will not stop automatically, but will aggravate the development

How many square kilometers does the land area of global desertification expand every year
Land area of global desertification

1. The total area of desertification land in China is 1.74 million square kilometers, accounting for 18.1% of the total land area, and it is still expanding at the rate of 3436 square kilometers every year, which is equivalent to losing a medium-sized county every year, and losing 4.5 mu of land almost every minute

How does our country control desertification?

First of all, the sand dunes can be fixed by laying grass squares and burying sand barriers to prevent further expansion of the desert. Second, the intensive management of land should be carried out, overgrazing should be strictly prohibited, rotation tillage and fallow should be advocated to maintain soil fertility. Third, the planting structure should be optimized, precision irrigation should be carried out conditionally, and advanced technologies such as Israel should be learned

What should we do about the desertification of the earth

1. Plant trees and grass
2. Adopt engineering measures to prevent the desert from expanding
3. Develop new energy (because desertification in many places is caused by people's deforestation. People's deforestation is because they cut firewood to go home for fuel)
4. Using agricultural technology to increase the single grain yield (in some places, it is necessary to expand the grain planting area by reclaiming wasteland indiscriminately)
5. Strengthen environmental awareness education
These are the main points

How to read Chinese land
Do you know this magical land,
Buried the golden Acacia,
Clusters of rhododendrons are in full bloom,
From the torrent of the Three Gorges comes the sigh of the goddess,
In winter, from permafrost to green coconut forest,
The rose waves caress the sand
Do you know this magical land,
Yellow skin, black hair is so beautiful,
Dunhou's character is like the lake under the breeze,
Tenacious and brave as the Yangtze River,
Under the frosted grapes, there is joy,
The hard core has opened the opportunity of rejuvenation
This is Liu zhanqiu's land of China. How can I read it? High and low voice, where can I pause? Please mark it for me,

/For pause, · for heavy treble, the rest can be low and medium tone
Do you know / this magical land,
· ·· ··
Buried / golden / Acacia,
····
A bunch / Rhododendron / colorful,
····
The Three Gorges of torrent / the sigh of goddess,
·· ·····
Winter / from permafrost / to green coconut forest,
······
The rose waves caress the sand
···· ···
Do you know / this magical land,
· ···
Yellow skin, black hair / so beautiful,
····
Honest character / like the lake in the breeze,
·
Tenacious and brave, like the Yangtze River,
····
Under the frosty grapes / dancing with joy,
··· ··
The hard core / has opened / a chance of revival
·· ········

Given (M + n) - 2 (M + n) + 1 = 0, find the power of (M + n) in 2012

In order to see clearly
Let m + n = X
x2-2x+1=0
(x-1)2=0
x=1
That is, M + n = 1
2012 power of (M + n) = 1

How many significant digits does the approximate number 1.02 × 10 ^ 5 have? To what point is it accurate?

There are three significant numbers, accurate to thousands

The approximate number is 9.105 × 10 Yes, there are A significant number, plus

Accurate to the hundredth, there are four significant digits 9, 1, 0, 5
For an approximate number, from the first number on the left that is not zero to the exact number of digits, all numbers are called the significant digits of the number