Một dung dich có nồng độ H+ bằng 0,001M thì pH và [ H+ ] của dung dịch này là ?

Tìm x, biết: (x+1)+(2x+3)+(3x+5)+...+(100x+199)=30200

Đọc và khoanh đúng Having a best friend to consider in can bring a positive effect on our emotional healthy. An evening out with the closest friend may be the best guarantee of a good time. In fact, our best friend can prevent us from developing serious psychological problems such as depression and anxiety. Best fiendships evolvest with time- we cannot go out and pick our best friend. We become friends with people who share common interests- at school or through hobbies, for example. Best friends have usually know each other for years and stuck together through good and bad times. If you haven't got one, perhaps you are being too distant from people, or for using too much on your work. 1. A best friend can_____ A. Give us a healthy life B. Go out with us in the evening C. Spend much time finding D. Share joy and sadness with us 2. Close friends need to_____ A. Study at the same school B. Have the same interests C. Pursue the same hobbies D. Spend time together 3. According to the passage,___ A. It takes a lot of time to make close friendships B. We can go out and choose a good friendships C. Best friends have good and bad times D. It's very difficult to make lasting friendships 4. The word' one' in the last paragraph refers to A.good time. B.bad time. C.friendship D. A close friend 5. Which of the following sentences is not mentioned? A. We often have satisfaction being with a close friend B. The times of close friendship will never be broken C. An unsociable person may not have a close friend D. Friendships need time to develop

VI.Supply the correct form of the words in brackets 1. Mike's hobby is listening to music. He gets a lot ... from listening to music. ( enjoy ) 2. John is a stamp ... . He has a lot of rare and valuable stamps (collect) 3. One third of children in the U.S is ... or obese (weigh) 4. I have ... so I must go to a dentist (tooth) 5. Junk food is ... ,so we shouldn't eat too much junk food (health) 6. Blood ... give blood for use in hospitals (donate) 7. They aren'n forced tondo charity work. They do it ... (volunteer) 8. They opened a shelter to provide housing for the ... (home) VII. Each sentence has a mistake . Find and correct it 1. My brother loves play chess when he has free time 2. I find woodcarving interest because it's creative 3. Many people wait for the dentist at the moment 4. They have donated blood three months ago 5. Did you finished your homework yet ? 6. I'd like to go, and I have to study for my test tonight 7. Eat more fast food, or you'll put on weight 8. Do you think staying at home all day is bored VIII. Put the verbs in brackets into the past simple or the present perfect 1.A: ...(you/ever/meet) anyone famous ? B: Yes, last summer I ... (sit) next to Brad Pit on a plane to LA. 2. A: How long ago ... (you/start) painting B: Ten years ago. I ...(recently/complete) a painting that the National Gallery ... (ask) me to do a year ago 3. A: last night, I ... (see) the latest James Bond film B: Oh, I .... (already/see) it twice 4. A: Do you know that Mrs Janet ... (work) here for sixteen years ? B: I thought she ... ( start) working here ten year ago IX. Put the verbs in brackets into the correct verb form 1. I (have ) ... dinner when his friend called 2. Joan( travel) ...around the world 3. We (not begin) ...to study for the test yet 4. Don't get on a bus while it ( run) ... 5. I (invite) ... them to my birthday party yesterday, however , they ( not come ) ... 6. Look! Somebody ( clean ) ... the room 7. My brother ( begin ) ...looking for a job in January 8. Timson ( make) ...13 films and I think her latest is the best 9. She ( cook) ...at the moment . That's why she can't answer the phone 10. She dosen'n mind ( go) ...out in the evening 11. I ( not see ) ...him since we ( leave ) ... school 12. Football ( be ) ...my favourite sport . I like (play) ...it in my free time 13. Jane( leave ) ...just a few minutes ago 14. She ( be ) ...extremely queit since her husband died Giúp mik với m.ng ơi

Bác Minh có 7 cây táo muốn trồng thành 6 hàng mỗi hàng có 3 cây Hãy giải bài này

x/2=y/3;y=4=z/5 và x-y-z=56 3x=y ; 5y =4z và 6x + 7y +8z = 456

Một lớp có 40 học sinh.trong đó có 1/10 số hs giỏi vẽ.2/10 số h/s giỏi tiếng vệt.3/10 số h/s giỏi toán.tính số h/s giỏi vẽ. Giỏi toán. Giỏi tiếng việt

Tìm x, biết: x+x-1+x-2+x-3+..+x-50=255

Xét biểu thức: $B=(x^{2}+1)(y^{2}+1)-(x+4)(x-4)-(y^{2}-25)$ CMR: $B\geq 42\forall x,y$. Với giá trị nào của x,y thì $B=42$

viết lại câu i'm telling you this for you not to make a mistake