Dầu chuối là este có tên isoamyl axetat, được điều chế từ

A. CH₃OH, CH₃COOH.

B. (CH₃)₂CH-CH₂OH, CH₃COOH

C. C₂H₅COOH, C₂H₅OH

D. CH₃COOH, (CH₃)₂CH-CH₂-CH₂OH

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 33 to 37.

ENGLISH SPEELING

Why does English spelling have a reputation for being difficult? English was first written down when Christian monks came to England in Anglo-Saxon (33) ______. They used the 23 letters of Latin to write down the sounds of Anglo-Saxon speech as they heard it. However, English has a (34) _____ range of basic sounds (over 40) than Latin. The alphabet was too small, and so combinations of letters were needed to express the different sounds. Inevitably, there were inconsistencies in the way that letters were combined.

With the Norman invasion of England, the English language was put at risk. English survived, but the spelling of many English words changed to follow French (35) _____, and many French words were introduced into the language. The result was more irregularity.

When the printing press was invented in the fifteenth century, many early printers of English texts spoke other first languages. They made little effort to respect English spelling. Although one of the shortterm (36) _____ of printing was to produce a number of variant spellings, in the long term it created fixed spellings. People became used to seeing words spelt in the same way. Rules were drawn up, and dictionaries were put together which printers and writers could refer to. However, spoken English was not fixed and continued to change slowly - just as it still does now. Letters that were sounded in the Anglo- Saxon period, like the 'k' in 'knife', now became (37) _____. Also, the pronunciation of vowels then had little in common with how they sound now, but the way they are spelt hasn't changed. No wonder, then, that it is often difficult to see the link between sound and spelling.

Điền vào ô số 33

A. centuries

B. times       

C. ages        

D. years 

Bạn Ngọc mua 4 cốc trà sữa. Số cốc trà sữa ở cửa hàng là bội số của số cốc bạn Ngọc mua. Tìm số cốc trà sữa ở cửa hàng? Biết số cốc trà sữa lớn hơn 116 và nhỏ hơn 123

Năm nay Bình 12 tuổi. Tuổi của mẹ Bình là bội số của tuổi Bình. Tìm tuổi của mẹ Bình biết tuổi của mẹ lớn hơn 30 và nhỏ hơn 45

Có 10 chiếc bánh trung thu. Bạn Ngọc muốn chia đều số bánh vào các hộp. Tìm số hộp và số bánh trong mỗi hộp? Biết số bánh ở mỗi hộp phải nhiều hơn 1 và ít hơn 10

Tìm số tự nhiên n để các số sau nguyên tố cùng nhau:

a, 7n+13 và 2n+4

b, 4n+3 và 2n+3

Mark the letter A, B, C, or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions

A. chamber

B. ancient

C. danger 

D. ancestor 

Chứng minh rằng với mọi số tự nhiên n thì các số sau nguyên tố cùng nhau:

a, 2n+3 và 4n+8

b, 2n+5 và 3n+7

c, 7n+10 và 5n+7