一个英语句式问题.
问题描述：
一个英语句式问题.
Cocoa contains chemicals called flavanols that may help reduce the risk of strokes and heart attacks bylowering blood pressure and bad cholesterol levels and improving the body's use of insulin.
请问上面的句子,我有一个不明白的地方,就是,我杆菌定语从句中,help和improve应该是并列的关系,请问原句中为什么用了improving
答
help与improve不是并列关系
lowering和improving才是并列关系.这两个词是在介词by后面所以改为动名词.