Questions 16 to 18 are based on the passage you have just heard.
16. A) They have small roots.
B) They grow white flowers.
C) They taste like apples.
D) They come from Central Africa.
17. A) They turned from white to purple in color.
B) They became popular on the world market.
C) They became an important food for humans.
D) They began to look like modern-day carrots.
18. A) They were found quite nutritious.
B) There were serious food shortages.
C) People discovered their medicinal value.
D) Farm machines helped lower their prices.
图片发自简书App
图片发自简书App
图片发自简书App
图片发自简书App
