brownfield和greenfield老师讲课似乎没有提到，请教分别的含义？
问题如下图：
选项：
A. 
B. 
C. 
解释：
NO.PZ2018053101000014 prectable cash flows. higher expectereturns. B is correct. A brownfielinvestment is investment in existing infrastructure asset, whiis more likely to have a history of stea cash flows comparewith thof a greenfielinvestment. Growth opportunities anreturns are expecteto lower for brownfielinvestments, whiare less risky thgreenfielinvestments. Brownfiel已经建成的成熟项目，此时稳定性好，现金流可预测，整体风险可控，B正确；同时对于brownfiel目一般比较稳定，通常不具备较高的增长性和高回报，所以A，C不正确。 知道greenfiel险更大，那会意味着收益比棕地更多吗？
老师 能麻烦 下 greenfiel和brownfiel？
好像没见过呀，棕色，绿色～～～
