EXERCISE 3I. CHỌN TỪ/ CỤM TỪ THÍCH HỢP (ỨNG VỚI A, B, C, D) ĐỂ HÒAN TH...

46. What is the main topic of the passage? A. The growth rate of hardwoods B. The transportation difficulties C. The number of useless trees D. The high costs of commercial lumbering in the tropics.