B={0,1,2,3,4}\(\subset\)A={0,1,2,3,4,5,6,7,8,9}

1. A. garden B. yard C. market D. warm
2. A. aerobics B. carrot C. lemonade D. correct
3. A. armchair B. sandwich C. chocolate D. school
4. A. ahead B. white C. behind D. hungry
5. A. stadium B. accident C. finally D. animal

Ta đặt:

A + A + A = 90

A + 2B + 2B = 230

C + 2B + A = 210

B - A + C =?

Vậy: A + A + A = 90 3A = 90 A = 30

A + 2B + 2B = 230 30 + 4B = 230 B = 50

C + 2B + A = 210 C + 100 + 30 = 210 C = 80

\(\Rightarrow\) B - A + C = 50 - 30 + 80 = 100

số các số hạng là :

( 100 - 1 ) : 1 + 1 = 100 ( số )

tổng là :

( 100 + 1 ) x 100 : 2 = 5050

                        đs : 5050

Vì những hoa nhỏ thường mọc thành cụm có tác dụng thu hút sâu bọ và có lợi cho sự thụ phấn của hoa. Sâu bọ từ xa đã có thể phát hiện ra chúng nên bay đến hút mật hoặc lấy phấn rồi lại bay sang hoa khác, chính vì thế có thể giúp cho nhiều hoa được thụ phấn, quả sẽ đậu được nhiều hơn.

Ho Chi Minh City is the largest city and the region’s centre for economics, education and culture in Vietnam.
First, it is located in the south-eastern region of Vietnam with a tropical climate, specifically a tropical wet and dry climate. The city's location on the Saigon River makes it a bustling commercial and passenger port, besides a constant stream of cargo ships, passenger boats operate regularly between Ho Chi Minh City and various destinations in Southern Vietnam.
Second, Ho Chi Minh City is a large industrial center with more than 600 state enterprises, 20.000 private producing establishment, not to mention the businesses with foreign invested capitals, with numerous forms of production and diversified occupations. So it has high population density with many people from many areas in Vietnam comes and works together.
Next, Ho Chi Minh City has emerged as Viet Nam's main commercial hub and an important motor of economic growth both regionally and nationally. This city has a diversified network of shopping centre, super market, market-day,... Specially, the weekend fairs in HCM City are not only shopping places for young people, but also a destination for sightseeing and shopping for many foreign tourists where people not only can buy supplies but also can buy souvenirs.

Along with jogging and swimming, cycling is one of the best all-round forms of exercise. It can help to increase your strength and energy, giving you more efficient muscles and stronger heart. But increasing your strength is not the only advantage of cycling. Because you are not carrying the weight of your body on your feet, it’s a good form of exercise for people with painful feet or backs. However, with all forms of exercise it’s important to start slowly and build up gently. Doing too much and too quickly can damage muscles that aren’t used to working. If you have any doubts about taking up cycling for health reasons, talk to your doctor and ask his/her advice.

Thông, pơ mu được xếp vào nhóm hạt trần vì có hạt nằm lộ trên lá noãn hở, thông chưa có hoa và quả.

Cạnh hình lập phương 6dm
\(\Rightarrow\) Chiều cao 6 dm
\(\Rightarrow\) Chiều rộng = 6dm -1,2dm = 4,8dm
\(\Rightarrow\) Chiều dài 4,8 x 1, 5 =7,2dm
\(\Rightarrow\) Stp = (6 x 7,2 + 6 x 4,8 + 7,2 x 4,8) x 2 = 213,12 dm²