托福考试

【单选题】What does the professor mean when he says this
A、Little is known about defining a substance as an air pollutant.
B、The substance isn’t an air pollutant when there is a very little in the air.
C、The substance can’t be judged to be an air pollutant only from its actual concentration level.
D、The actual concentration level means little to peopl

网考网参考答案：C
网考网解析：
[解析] 本题为语用理解题，考查考生是否能听懂说话者说话的意图。题目问：教授说这一段话是什么意思 原文第三段提到“The actual concentration need not be large for a substance to be a pollutant; in fact the concentration tells us little until we know how much of an increase this represents over the concentration that would occur naturally in the area”，这段话的大意是：只有知道这种物质的实际含量比空气中的自然含量增加了多少才能断定它是不是污染物，因此C项为正确答案。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>