Hỗn hợp A gồm anđehit acrylic và một anđehit đơn chức X. Đốt cháy hoàn toàn 19,04 gam hỗn hợp trên cần vừa hết 29,792 lít khí oxi (đktc). Cho toàn bộ sản phẩm cháy hấp thụ hết vào dung dịch Ca(OH)₂ dư, thu được 104 gam kết tủa. CTCT thu gọn của X là

A. HCHO  

B. C₂H₃CHO        

C. C₂H₅CHO        

D. C₃H₇CHO

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 first each of the numbered blank from 1 to 5

 American folk music originated with (1) _____ people at a time when the rural population was isolated and music was not (2)______spread by radio, records, or music video. It was (3)_____by oral traditional and is noted for its energy ,humor, and emotional impact. The major source of aerly American folk songs was music from the Bristish Isles , but songs from Africa as songs of the American Indians have significant part in its heritage. Later settler from other countries also contributed songs. In the nineteenth century, composer Steven Foster wrote some of the most enduringly popular of all American songs ,(4)______soon became part of the folk tradition. Beginning in the 1930s , Woody Guthrie gained great popularity by adapting melodies and lyrics and supplying new ones as well. In the 1950s and 1960s , singer – composers such as Peter Seeger , Bob Dylan , Joan Baez continued this tradition by „urban’ folk music. Many of these songs deal (5)_____important social issue, such as racial intergration and the war in Vietnam.

Điền vào ô 2.

A. yet

B. still

C. until

D. even