Cứ mỗi sáng thứ 2 đầu tuần, em lại háo hức mong chờ được đến trường để tham dự buổi l

Drought is a natural phenomenon considered a natural disaster, caused by a severe shortage of rainfall for a long time, reducing the moisture content in the air and the water content in the soil, depleting the river flow. streams, lowering water levels in ponds and lakes, water levels in underground aquifers, adversely affecting the growth of crops, degrading the environment, causing poverty and epidemics ... if arranged in the order of Globally, property damage and lives, drought ranks fourth after floods, earthquakes and storms. Particularly for the Central Highlands region, drought is a natural disaster that has the most negative impact on life and production. Causes of drought Due to the unusual weather, the rainfall shortfall is often prolonged or temporary shortage Very little rain, negligible rainfall for a long time almost year round, this is common in arid and semi-arid regions. Rainfall over a long period of time is significantly lower than the average of many years in the same period. This situation can occur in almost all regions, including heavy rain areas. Not very little rain, but for a certain time before that no rain or rain only met the minimum needs of production and surroundings. This is a common situation in monsoon climatic regions, with a clear difference in rainfall between the wet and dry seasons. Forest fire-Photo V.Nhien. Caused by humans: First of all, indiscriminate deforestation reduces the ability to regulate surface water, lowering groundwater levels, leading to depletion of water resources; The cultivation of trees is not suitable, the areas with less water are also growing crops that require a lot of water (such as rice), making water use too much, leading to the depletion of water resources; in addition, the planning of water use, the layout of the works is not suitable, making many works not effective ... The region needs a lot of water to arrange small works, the area lacks water (source natural water) to re-arrange large works. Besides, the quality of construction design and construction has not been modernized and is not suitable. In addition, water shortage droughts in the dry season are caused by insufficient water resources and the lack of necessary measures to meet the increasing demand for use due to socio-economic development in the regions and regions. the region has not had proper planning or development plan is not suitable with the level of water resource development, not in harmony with nature and environment which has existed for a long time. The severity of water shortage drought is increasing because vulnerable and degraded water sources are strongly influenced by people. Harms of drought Drought has a great impact on the environment, economy, socio-politics and human health. Drought is the cause of poverty, disease, even war due to water conflicts. Droughts affect the environment such as destroying plants, animals, wildlife populations, reducing air and water quality, increasing the risk of forest fires and soil erosion. These effects can be long and irreversible. Drought affects the socio-economy such as reducing crop productivity, reducing cultivated area, reducing crop yield, mainly food crop yield. Increase agricultural production costs, reduce income of agricultural labor. Increasing the costs and prices of food. Reduce the total value of livestock products. Hydropower plants have many difficulties in the operation process. Drought is characterized by slow formation, long impact time, negative impacts on many areas including daily life, production, environment, etc. In the Central Highlands almost every year drought is threatened. In a normal or fairly rainy year, the Central Highlands also experience several or three dry months (usually from mid-January to early April) with over two thirds of areas affected by drought and water shortage. This is the period when the lowest humidity, rainfall and runoff amount in the year is also the peak period of hot weather. The annual rainfall is characterized by a large variation around the mean value (a year with heavy rainfall may be twice as much as a year with little rain), and the amount of flow in rivers and streams depends mainly on rainfall. With little rain, drought and lack of water in the adjacent dry season is very severe. The frequency of severe drought years in the Central Highlands exceeds 20%, or about 5 years there is a year of severe or particularly severe drought. Dry dams-Photo VP Term forecast Unlike other natural disasters, drought develops slowly and is usually only discovered when people have been more or less affected by drought. Up to now, scientists have outlined a number of important scientific bases that help in term prediction such as: Interaction ocean atmosphere and Elnino phenomenon. The Elnino and Lanina that occur in the equatorial Pacific are closely related to a dramatic increase or decrease in precipitation in the surrounding Pacific, especially in the tropics. In our country, the Elnino effect tends to increase the possibility of droughts in some areas, in which the Central Highlands has the 

1.a

2.a

3.d

4.c

5.d

Năng lượng đầu vào là điện năng

Năng lượng đầu ra là nhiệt

Khối đa diện được bao bởi các hình đa giác phẳng. Mỗi hình chiếu của khối đa diện trên mặt phẳng chiếu thể hiện được hai trong ba kích thước của khối đa diện: chiều dài, chiều rộng, chiều cao 

 Tư thế đứng: Người cưa đứng thẳng, thoải mái, khối lượng cơ thể phân đều lên 2 chân, chân phải hợp với chân trái 1 góc 75° , chân phải hợp với trục của êtô 1 góc 45°

- Thao tác có bản khi cưa: 

+ Cầm cưa: Tay phải nắm cán cưa, tay trái nắm đầu kia của khung cưa.

+ Thao tác: Kết hợp hai tay và một phần khối lượng cơ thể để đẩy và kéo cưa. Khi đẩy thì ấn lưỡi cưa và đẩy từ từ để tạo lực cắt, khi kéo cưa về, tay trái không ấn, tay phải rút cưa về nhanh hơn lúc đẩy, quá trình lặp đi lặp lại như vậy cho đến khi kết thúc.

đáp án B

3 nội dung

• Xác định nhu cầu sử dụng mạch điện


•  Đưa ra các phương án mạch điện (vẽ sơ đồ nguyên lý)


•  Xác định những phần tử cần thiết để lắp điện

đáp án B

thuộc bước A

Luật này có hiệu lực thi hành kể từ ngày 01 tháng 01 năm 1999 và thay thế Luật quốc tịch Việt Nam ngày 28 tháng 6 năm 1988. Chính phủ quy định chi tiết và hướng dẫn thi hành Luật này. Luật này đã được Quốc hội nước Cộng hòa xã hội chủ nghĩa Việt Nam khóa X, kỳ họp thứ 3 thông qua ngày 20 tháng 5 năm 1998.

3

1+1=2

.