Cho hình vẽ điều chế khí Y từ chất rắn X. Phương trình phản ứng nào sau đây là đúng:

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

(A) Not until ten years (B) ago (C) was there much need for personal (D) computer.

A. Not until

B. ago 

C. was there 

D. computer

Mark the letter A, B, C, or D on your answer sheet to indicate the word that differs from the other three in the position of primary stress in each of the following questions

A. comfortable     

B. powerful          

C. opinion  

D. accurate