Read the following passage and choose the letter A, B, C, or D to indicate the correct word or phrase that best fits each of the numbers blanks
Plants provide food, clothing, and shelter for people. Many of our most useful medicines are also (31) _____ from plants. Besides, plants add beauty and pleasure (32) _____ our lives. Most people enjoy the smell of flowers, the sight field of waving grain, and the quiet of a forest. Not all plants are helpful to man. Some species grow in fields and gardens as weeds that choke off useful plants. Tiny hits of pollen from certain plants cause such (33) _____ as asthma and hay fever. Some plants are (34) ______ if we eat them. (35) _______ irritate the skin.
(31) ...............
