Bài 3. Cho tam giác ABC đường cao BK và CI cắt nhau tại H. Các đường thẳng kẻ từ B vuông góc với AB và kẻ từ C vuông góc với AC cắt nhau tại D . a) Chứng minh tứ giác BHCD là hình bình hành . b) Chứng minh AI . AB = AK . AC c) Chứng minh tam giác AIK và ACB đồng dạng . d) Tam giác ABC cần có điều kiện gì để đường thẳng DH đi qua A ? Khi đó tứ giác BHCD là hình gì ?

Rút gọn biểu thức. C=(x+2/2-x+4x^2/4-x^2-2-x/x+2):x^2-x/2x-x^2

bánh dẫn có 63 răng bánh bị dẫn có 21 răng vận tốc bánh dẫn là 4 vòng/phút.Tính vẫn tốc bánh bị dẫn

Nowadays, students are addicted to social networks, so it causes them a lack of direct communication with the outside world.

A. Nowadays, being addicted to social networks causes students a lack of direct communication with the outside world.

B. Nowadays, students are addicted to social networks, because it causes them a lack of direct communication with the outside world.

C. Nowadays, students are addicted to social networks , it causes them a lack of direct communication with the outside world.

D. Nowadays, it causes students a lack of direct communication with the outside world.

A. 25.____________ to Mars might become a reality sooner than you think. Scientists are planning to send people (not animals!) to  26.____________ Mars in the near future. They believe it’s the only way to find out if there is, or ever has been, life on this planet. They will explore the 27.____________ of living there. So people may go there to live one day!

B. Scientists say that in the future people will live longer. Incurable diseases will be 28.____________ and ‘bad’ genes will probably be replaced. With healthier lifestyles and better 29.____________ care the average person will live to be 100 instead of 70 (for men) or 75 (for women) like today. Anti-ageing pills will also be invented to help people live longer.

C. 30. ____________ homes will be located on the ocean, in the air, or underground. These homes will have advanced 31.____________ saving devices such as solar panels, solar windows, and smart home technology. Future homes will take advantage of robots to do 32.____________ such as cleaning, cooking, washing, and organizing everything for their owners.

25. A. Travelling            B. Visiting                      C. Living              D. Fly

26. A. find                      B. explore                       C. do research       D. learn

27. A. able                      B. possible                      C. possibility         D. chance

28. A. taken                    B. cure                            C. treat                  D. cured 

29. A. medicine               B. healthy                       C. medical             D. fit

30. A. Old-fashioned       B. Future                         C. Ancient             D. Outdated

31. A. sources                 B. energy                        C. earth                 D. coal

32. A. housework            B. household chores        C. chores               D. all choices A,B,C

A. 25.____________ to Mars might become a reality sooner than you think. Scientists are planning to send people (not animals!) to  26.____________ Mars in the near future. They believe it’s the only way to find out if there is, or ever has been, life on this planet. They will explore the 27.____________ of living there. So people may go there to live one day!

B. Scientists say that in the future people will live longer. Incurable diseases will be 28.____________ and ‘bad’ genes will probably be replaced. With healthier lifestyles and better 29.____________ care the average person will live to be 100 instead of 70 (for men) or 75 (for women) like today. Anti-ageing pills will also be invented to help people live longer.

C. 30. ____________ homes will be located on the ocean, in the air, or underground. These homes will have advanced 31.____________ saving devices such as solar panels, solar windows, and smart home technology. Future homes will take advantage of robots to do 32.____________ such as cleaning, cooking, washing, and organizing everything for their owners.

25. A. Travelling            B. Visiting                      C. Living              D. Fly

26. A. find                      B. explore                       C. do research       D. learn

27. A. able                      B. possible                      C. possibility         D. chance

28. A. taken                    B. cure                            C. treat                  D. cured 

29. A. medicine               B. healthy                       C. medical             D. fit

30. A. Old-fashioned       B. Future                         C. Ancient             D. Outdated

31. A. sources                 B. energy                        C. earth                 D. coal

32. A. housework            B. household chores        C. chores               D. all choices A,B,C

A. 25.____________ to Mars might become a reality sooner than you think. Scientists are planning to send people (not animals!) to  26.____________ Mars in the near future. They believe it’s the only way to find out if there is, or ever has been, life on this planet. They will explore the 27.____________ of living there. So people may go there to live one day!

B. Scientists say that in the future people will live longer. Incurable diseases will be 28.____________ and ‘bad’ genes will probably be replaced. With healthier lifestyles and better 29.____________ care the average person will live to be 100 instead of 70 (for men) or 75 (for women) like today. Anti-ageing pills will also be invented to help people live longer.

C. 30. ____________ homes will be located on the ocean, in the air, or underground. These homes will have advanced 31.____________ saving devices such as solar panels, solar windows, and smart home technology. Future homes will take advantage of robots to do 32.____________ such as cleaning, cooking, washing, and organizing everything for their owners.

25. A. Travelling            B. Visiting                      C. Living              D. Fly

26. A. find                      B. explore                       C. do research       D. learn

27. A. able                      B. possible                      C. possibility         D. chance

28. A. taken                    B. cure                            C. treat                  D. cured 

29. A. medicine               B. healthy                       C. medical             D. fit

30. A. Old-fashioned       B. Future                         C. Ancient             D. Outdated

31. A. sources                 B. energy                        C. earth                 D. coal

32. A. housework            B. household chores        C. chores               D. all choices A,B,C