第二章测试1.How many types of bacteria can be found in a spoonful of good soil?（ ）
A:750,000 B:75,000 C:7,500,000 D:7,500
答案:B
2.How many soil layers typically make up mature soil?（ ）
A:3 B:1 C:4 D:2
答案:A
3.What role does soil play in the carbon cycle?（ ）
A:Important water resource B:Important carbon storage C:Strengthening carbon sinks D:Important energy source
答案:B
4.What percentage of soil is made up of pores?（ ）
A:50% B:75% C:10% D:25%
答案:A
5.What are the three principal characteristics of light that affect plant growth? （ ）
A:Concentration, spectrum, and time B:Quantity, quality, and duration C:Brightness, wavelength, and period D:Intensity, color, and frequency
答案:B
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