Cá heo và cá voi được xét vào lớp thú vì:

- Đẻ con và nuôi con bằng sữa

- Cơ thể được bao phủ lớp lông mao

- Là động vật có vú

Read the following passage and choose A, B, C, or D to indicate the correct word or phrase that best fits each of the following blanks. Fill in the appropriate word in question 32

Parents whose children show a special interest in a particular sport have a difficult decision to (31) ______ about their children’s career. Should they allow their children to train to become top sportsmen and women? For many children it (32) ______starting very young and school work, going out with friends and other interests have to take second place. It’s very difficult to explain to a young child why he or she has to train for five hours a day, even at the weekend, when most of his or her friends are playing.

Another problem is of course money. In many countries money for training is (33) ______ from the government for the very best young sportsmen and women. If this help cannot be given, it means that it is the parents that have to find the time and the money to support their child’s development- and sports clothes, transport to competitions, special equipment etc. can all be very expensive.

Many parents are understandably concerned that it is dangerous to start serious training in a sport (34)_____ an early age. Some doctors agree that young muscles may be damaged by training before they are properly developed. Professional trainers, however, believe that it is only by starting young that you can reach the top as a successful sports person. What is clear is that very (35) _______ people reach the top and both parents and children should be prepared for failure even after many years of training.

A. should

B. means

C. helps

D. tries

Thị giác : nhìn

Vị giác :cảm nhận vị

Xúc giác : cảm nhận

Khứu giác : ngửi

Chúng được gọi là cơ quan phân tích vì:

Xét về cơ quan phân tích thì có 3 cơ quan tương ứng với 5 giác quan . Nói cách khác thì 5 giác quan đều đảm nhận 1 vai trò hay chúng chính là cơ quan phân tích

\(\Leftrightarrow|x+\dfrac{4}{5}|=\dfrac{6}{5}+\dfrac{3}{5}\)

\(\Leftrightarrow|x+\dfrac{4}{5}|=\dfrac{9}{5}\)

*TH1: \(x+\dfrac{4}{5}\le0\)(1)

(1) \(\Leftrightarrow-\left(x+\dfrac{4}{5}\right)=\dfrac{9}{5}\)

\(\Leftrightarrow-x-\dfrac{4}{5}=\dfrac{9}{5}\)

\(\Leftrightarrow x=-\dfrac{9}{5}-\dfrac{4}{5}\)

\(\Leftrightarrow x=-\dfrac{13}{5}\)

*TH2: \(x+\dfrac{4}{5}\ge0\left(2\right)\)

(2)\(\Leftrightarrow x+\dfrac{4}{5}=\dfrac{9}{5}\)

\(\Leftrightarrow x=\dfrac{9}{5}-\dfrac{4}{5}\)

\(\Leftrightarrow x=1\)

Vì x la số nguyên

=>Không có giá trị của x thoả mãn đề bài

Cho 9,1 gam chất hữu cơ X có công thức phân tử C₃H₉O₂N phản ứng với 100 ml dung dịch NaOH 1,5M. Sau khi phản ứng xảy ra hoàn toàn, cô cạn dung dịch thu được 10,2 gam chất rắn khan. Công thức cấu tạo thu gọn của X là

A. C₂H₅COONH₄

B. CH₃COONH₃CH₃

C. CH₃CH(NH₂)COOH

D. HCOONH₃C₂H₅