cân bằng và cho bt phản ứng nào là phản ứng hóa hợp , phản ứng phân hủy

KClO3=> KCl+O2

Na+O2=>Na2O

Hgo=>Hg+O2

Fe(OH3)=>Fe2O3+H2O

tính 

a.

b.

c.

tính 

a.

b.

c.

Read the following passage then answer the questions.

Alaska is perhaps the most amazing state in the USA. It has coaslines facing both the Arctic Ocean and the Pacific Ocean. This state has an incredible three million lakes. That’s four lakes per person living there.

Many cities in Alaska cannot be reached by road, sea, or river. The only way to get it and out is by air, on foot, or by dogsled. That’s why Alaska has the busiest sea airport in the world, Lake Hood Seaplane Base. Nearly two hundred float planes take off and land on the water of this airport every day. It’s really a fun scene to watch.

Alaska is called the Land of Midnight Sun because in summer, the sun does not set for nearly three months. But in winter the sun stays almost unseen.

   All Alaskans take place special pride in their beautiful and unique state.

27. Where is Alaska?

……………………………………………………………………………………………

28. Does it have a lot of lakes?

……………………………………………………………………………………………

29. How do we get there?

……………………………………………………………………………………………

30. Why is Alaska called the Land of Midnight Sun?

……………………………………………………………………………………………

Nêu 2 ví dụ về câu đặc biệt và rút gọn 

Một thửa ruộng hình thang có đáy bé 45m , đáy lớn bằng đáy bé . Chiều cao bằng đáy lớn . Tính diện tích thửa ruộng đó