When he--the wetland,he--many birds.A.walk through;see B.will walk past;will see;
问题描述：
When he--the wetland,he--many birds.A.walk through;see B.will walk past;will see;
C:walks cross;sees D.walks through;will see
答
D
主语是单三,且前空为从句,排除A/B
排除C walk across为词组,而walk与 cross均为动词.可是wetland前不应该用through啊不对！walk across与 walk through的区别在于：前者从表面，后者从内部。假如wetland上没植物，用across，而wetland上有芦苇等植物，需用through。