VII. Read the text quickly and complete the information in the table.

GREAT LAKES OF THE WORLD

The oldest lake in the world Lake Baikal is 25-30 million years old-the oldest lake in the world. It holds 20 percent of the planet's surface freshwater. It is 650km long and nearly 2km deep.

Lake Baikal is in eastern Shiberia where the winters are very cold. Temperatures average minus 20 degrees. The lake freezes for five months or more of the year. The ice is 1,2m thick, and trucks drive across the lake when it freezes.

The lake has more than 1,200 species of animals and 1,000 species of plants.

It is home to the world's only freshwater seal, the nerpa. There are approximately 50,000 nerpas in the lake. Nerpas can dive down 300m to catch fish!

Giant Lakes

The world's largest lake in the Caspian Sea in south-west Asia. It is 370,000 sq km. It is salt water and not freshwater. The world's largest freshwater lake is Lake Superior, one of the Great Lakes of North America. These lakes are the biggest mass of freshwater in the world.

Stories about lakes

Scotland's Loch Ness is famous for its 'monster', and is only 230m deep. But Lake Nicaragua in Central America is home to the dangerous bull shark, which is more than 3m long. The sharks swim up and down the San Juan River into the Caribbean Sea.

Read the text again and answer the questions:

6. How old is Lake Baikal?

7. How long is Lake Baikal?

8. What happens to Lake Baikal in the winter?

9. What is the name of the seal that lives in Lake Baikal?

10. Why does the seal dive deep into the lake?

11. Is Lake Superior freshwater ỏ salt water?

12. What is Loch Ness famous for?

VII. Read the text quickly and complete the information in the table.

GREAT LAKES OF THE WORLD

The oldest lake in the world Lake Baikal is 25-30 million years old-the oldest lake in the world. It holds 20 percent of the planet's surface freshwater. It is 650km long and nearly 2km deep.

Lake Baikal is in eastern Shiberia where the winters are very cold. Temperatures average minus 20 degrees. The lake freezes for five months or more of the year. The ice is 1,2m thick, and trucks drive across the lake when it freezes.

The lake has more than 1,200 species of animals and 1,000 species of plants.

It is home to the world's only freshwater seal, the nerpa. There are approximately 50,000 nerpas in the lake. Nerpas can dive down 300m to catch fish!

Giant Lakes

The world's largest lake in the Caspian Sea in south-west Asia. It is 370,000 sq km. It is salt water and not freshwater. The world's largest freshwater lake is Lake Superior, one of the Great Lakes of North America. These lakes are the biggest mass of freshwater in the world.

Stories about lakes

Scotland's Loch Ness is famous for its 'monster', and is only 230m deep. But Lake Nicaragua in Central America is home to the dangerous bull shark, which is more than 3m long. The sharks swim up and down the San Juan River into the Caribbean Sea.

Lần lượt treo vào cùng một lò xo các vật có khối lượng sau: m₁=1kg;m₂=1,5kg;m₃=0,8kg. Em hãy cho biết trường hợp nào độ biến dạng của lò xo là lớn nhất, nhỏ nhất? Giải thích.

Với a∈Z, hãy so sánh a² và 2a

Tìm xZ biết:

a)-2x-11 chia hết cho 3x+2