we study the birds by() A.doing bird count B.counting them 选哪个?为什么?
问题描述：
we study the birds by() A.doing bird count B.counting them 选哪个?为什么?
答
应该选B
选A有语法错误,应该是by doing a bird count,count是可数名词,所以不可缺少定冠词a
选B是正确的