Read the following passage, then choose the correct answer to questions 26 - 30.
Plants supply man with food clothing, and shelter- his most important needs.
Many of our most useful medicines are also made (26)_________plants. In addition, plants add beauty and pleasure to our lives. Most people enjoy the smell of flowers, the sight field of waving grain, and the quiet of a forest. Not (27)_______plants are helpful to man. Some species grow in fields and gardens as weeds that choke off useful plants. Tiny hits of pollen from (28)_______plants cause such (29)_________as asthma and hay fever. Other plants destroy millions of dollars (30)_______of crops yearly.
Trả lời câu hỏi dưới đây:
___________(30)
Other plants destroy millions of dollars (30)_______of crops yearly. (Các cây thực vật khác phá hủy hàng triệu đô la (30) _______of cây trồng hàng năm).
Đáp án là A. Worth = Số lượng cái gì mua được bằng một khoản tiền nào đó. Ví dụ : ten pounds' worth of petrol = mười pao ét xăng.