Are you sure you can do it on________?

A. youself

B. secret

C. your own

D. date

 Xét tính đúng sai của mỗi mệnh đề sau và phát biểu mệnh đề phủ định của nó: π < 3,15

Hợp chất NH₂–CH(CH₃) – COOH có tên gọi là

A. Valin

B. Glyxin

C. Alanin 

D. Lysin

Kí hiệu viết tắt Glu là chỉ chất amino axit có tên là:

A. axit glutamic

B. axit glutaric

C. glyxin

D. glutamin

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 67 to 76.

Ralph Earl was born into a Connecticut farm family in 1751. He chose early to become a painter and looked for what training was available in his home state an in Boston. Earl was one of the first American artists to paint landscapes. Among his first paintings were scenes from the Revolutionary war battles of Lexington and Concord In 1778 Earl went to London to study with Benjamin West for four years.

When Earl returned to the United States, he was jailed for fourteen months for outstanding debts. While still a prisoner, he painted portraits of some of New York City's most elegant society women and their husbands. After his release, he took up the trade of itinerant portrait painter, working his way through southern New England and New York. He didn't flatter his subjects, but his portrait show a deep understanding of them; perhaps he had sprung from the same roots.

Among Earl's most famous paintings is his portrait of Justice Oliver Ellsworth and his wife, Abigail. To provide counterpoint to the severity of the couple, he accurately details the relative luxury of the Ellsworth's interior furnishings. The view through the window behind them shows sun lit fields, well-kept fences, and a bend of the Connecticut River. One of Earl's paintings is something of anomaly. Reclining Hunter, which many years was attributed to Thomas Gainsborough, shows a well-dressed gentleman resting beneath a tree. In the foreground, he displays a pile of birds, the results of a day's hunt. The viewer can also see a farmer's donkey lying in the ground, another of the hunter's victims. This outrageously funny portrait couldn't have been commissioned - no one would have wanted to be portrayed in such an absurd way. However, this painting uncharacteristically shows Earl's wit as well as his uncommon technical skills.

The word “he” refers to________.

A. the farmer

B. the hunter

C. Thomas Gainsborough

D. Ralph Earl

Nếu kích thước quần thể xuống dưới mức tối thiểu, quần thể dễ rơi vào trạng thái suy giảm dẫn tới diệt vong. Có bao nhiêu nguyên nhân đúng?

(1) Số lượng cá thể quá ít nên sự giao phối gần thường xảy ra, đe doạ sự tồn tại của quần thể.

(2) Sự hỗ trợ giữa các cá thể bị giảm, quần thể không có khả năng chống chọi với những thay đổi của môi trường.

(3) Khả năng sinh sản suy giảm do cá thể đực ít có cơ hội gặp nhau với cá thể cái.

(4) Sự cạnh tranh cùng loài làm suy giảm số lượng cá thể của loài dẫn tới diệt vong.

A. 3.

B. 2.

C. 1

D. 4.

Quá trình oxi hóa của phản ứng Fe  +  CuSO₄  ®  FeSO₄  +  Cu là

A. Fe²⁺  + 2e  ®  Fe.      

B. Cu²⁺  + 2e  ®  Cu.    

C. Fe  ®  Fe²⁺  + 2e.      

D. Cu  ®  Cu²⁺  + 2e.