9. What is the main form of sulfur taken up by plants through their roots? (A) Sulfur dioxide；(B)Sulfite；(C) Sulfate； (D) Glutathione

複選題7.Why is Arsenic accumulation a problem for rice? (A)Rice possess Si transporters that can also transport As(III) (B)Rice grows in paddy fields, under anaerobic conditions that enhance As bioavailability (C) Arsenic is toxic, and can enter the food chain through rice (D) Rice is very sensitive to As, and low concentration of As can impair the yield