Cho các chất sau :

(1) CH₃CH(NH₂)COOH             (2) CH₂=CH₂

(3) HOCH₂COOH                                               (4) HCHO và C₆H₅OH     

(5) HOCH₂CH₂OH và p-C₆H₄(COOH)₂            

(6) H₂N[CH₂]₆NH₂ và HOOC[CH₂]₄COOH

Các trường hợp có thể tham gia phản ứng trùng ngưng là

A. (1), (3), (4), (5), (6).

B. (1), (6).

C. (1), (3), (5), (6).

D. (1), (2), (3), (4), (5), (6).

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

The plan may be ingenious. It will never work in practice.

A. Ingenious as it may be, the plan will never work in practice

B. Ingenious as may the plan, it will never work in practice

C. The plan may be too ingenious to work in practice

D. The plan is as impractical as it is ingenious.

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. autumn

B. summer

C. public

D. struggle