As we approached the work site,the workers were seen_As we approached the work site,the workers were seen_the newv house.A.buildingB.buildC.builtD.to build选了D,想问问为什么选A不选D
问题描述：
As we approached the work site,the workers were seen_
As we approached the work site,the workers were seen_the newv house.
A.building
B.build
C.built
D.to build
选了D,想问问为什么选A不选D
答
see+v-ing 正在做X事
答
当我们接近建筑工地时,发现工人们正在干活
ing形式,表示当时看见某人正在做某事