题目

阅读理解Few fruits carry more health-promotingantioxidants （抗氧化剂） than blackcurrants（黑 加仑 ） .Widely grown in cooler parts of Europe, they are in high demand from consumersseeking chemical-free juices made from the berries. Farmers, though, can struggle to increaseproductions without relying on chemicals.That could change, not just for blackcurrants butother fruit too,withthe careful use of probiotics（益生菌） . Probiotics is mostly known for its useof tiny 1iving things, including certain bacteria, to restore or improve thedigestion in people and animals. But pl下列各组单项式中，是同类项的是 （ ）A．－a2与(－a) 2B．2a2b与C．xyz与2xyD．3x2y与3x2z