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21 giờ trước (10:01)

-1.75

17 giờ trước (14:25)

0,75 + (- \(\frac52\)) = 0,75 - 2,5 = - 1,75

III. Read the text and choose the most suitable heading (A-G) for each paragraph (1-5). There are two extra headings that you do not need. (5pts) KEEPING OUR TEETH HEALTHY A. You can fill small holes in your teeth. B. Something you eat is good for your teeth, but something isn’t. C. Strong teeth are necessary for our health and appearance. D. Chocolate, sweets and biscuits are sometimes used after meals. E. Toothbrush and toothpaste help clean your teeth. F. Tooth decay makes our teeth bad....
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III. Read the text and choose the most suitable heading (A-G) for each paragraph (1-5). There are two extra headings that you do not need. (5pts) KEEPING OUR TEETH HEALTHY A. You can fill small holes in your teeth. B. Something you eat is good for your teeth, but something isn’t. C. Strong teeth are necessary for our health and appearance. D. Chocolate, sweets and biscuits are sometimes used after meals. E. Toothbrush and toothpaste help clean your teeth. F. Tooth decay makes our teeth bad. G. You should go to the dentist at least two times a year. 71. It is very important to have healthy teeth. Good teeth help us to chew our food. They also help us to look nice. 72. How does a tooth go bad? The decay begins in a little crack in the enamel covering of the toot. This happens after germs and bits of food have collected there. Then the decay slowly spreads inside to tooth. Eventually, poison goes into the blood, and we may feel quite ill. 73. How can we keep out teeth healthy? First, we ought to visit our dentist twice a year. He can fill the small holes in our teeth before they destroy the teeth. He can examine our teeth to check that they are growing in the right way. Unfortunately, many people wait until they have toothache before they see a dentist. 74. Secondly, we should brush our teeth with a toothbrush and fluoride toothpaste at least twice a day – once after breakfast and once before we go to bed. We can also use wooden toothpicks to clean between our teeth after a meal. 75. Thirdly, we should eat food that is good for our teeth and our body: milk, cheese, fish, brown bread, potatoes, red rice, raw vegetables, and fresh fruit. Chocolate, sweets, biscuits and cakes are bad, especially when we eat them between meals. They are harmful because they stick to our teeth and cause decay. Your answers: 71____________ 72____________ 73___________ 74___________ 75___________

giúp mình với

1
14 tháng 2

mình phân ra rõ ràng dc ko e, a ko nhìn dc :v

11 giờ trước (20:22)

topic viết thư về j vậy bạn


11 giờ trước (20:28)

thư tả thành phố ạ


21 giờ trước (10:32)

những trường hợp có thể xảy ra là sấp hoặc ngửa


20 giờ trước (11:29)

1. Sấp hoặc ngửa.

2. có giá trị cao thì đứa khác thó mất.

Đúng ko ạ?

17 giờ trước (14:14)

Olm chào em, đây là toán nâng cao chuyên đề số nguyên tố, cấu trúc thi chuyên thi học sinh giỏi các cấp. Hôm nay, Olm sẽ hướng dẫn các em giải các dạng toán này bằng phương pháp đánh giá như sau:

Giải:

TH1: Nếu p = 2 ta có: p + 2 = 2 + 2 = 4 (loại)

Vì 4 không phải là số nguyên tố.

TH2: Nếu p = 3 ta có: p + 2 = 3 + 2 = 5

2p + 5 = 2.3 + 5 = 11

TH3: Nếu p > 3 ta có:

p = 3k + 1 hoặc p = 3k + 2

Nếu p = 3k + 1 thì:

p + 2 = 3k + 1 + 2 = 3k + (1+2) = 3k + 3 ⋮ 3 (loại)

Nếu p = 3k + 2 thì:

2p + 5 = 2.(3k + 2) + 5 = 6k + 4 + 5

2p + 5 = 6k + (4 + 5) = 6k + 9 ⋮ 3 (loại)

Từ những lập luận trên ta có p = 3 là giá trị duy nhất thỏa mãn đề bài.

Vậy p = 3.






21 giờ trước (9:53)

B(45)={0;45;90;135;180;225;...}


21 giờ trước (9:54)

Bội của 45 là số có dạng:

45k (k ∈ Z)