[問題] Prep T1 Q17

[craigchsieh]

某位同學來信詢問：
17.(27669-!-item-!-188;#058&003302) 植物在城市比在鄉村長得慢
D選項為何對?感覺只在解釋
Urban air contains more sulfur dioxide than does rural air, and plants in cities typically grow more slowly than do plants in rural areas. In an experiment to see how much of the difference in growth is due to sulfur dioxide, classes in an urban and a rural school grew plants in greenhouses at their schools and filtered the greenhouse air to eliminate sulfur dioxide. Plants in the urban greenhouse grew more slowly than those in the rural greenhouse.

Which of the following, if true, would it be most important to take into account in evaluating the result?

(D) Heavy vehicular traffic such as is found in cities constantly deposits grime on greenhouse windows, reducing the amount of light that reaches the plants inside. 感覺只是在explain


Craig：D是在解釋沒錯，題目要求解釋（take into account）排除sulfur dioxide後的實驗結果為何兩地仍有差異。