第9题: [填空题]AlCl
3
、MgSO
4
、Na
3
PO
4
三种物质对土壤溶胶聚沉能力的大小次序是______。
参考答案:AlCl
3
>MgSO
4
>Na
3
PO
4
[解析] 土壤胶粒带负电,故答案为:AlCl
3
>MgSO
4
>Na
3
PO
4
第10题: [单项选择]In the suction stroke, the crankshaft is rotating clockwise and the piston is moving () the cylinderThe inlet valve is () and a fresh charge of air is being drawn or pushed into the cylinder by the turbocharger. A. up;opened B. down;open C. up;closed D. down;closed 参考答案:B