By_____(do)a lot of exercise,he became stronger and taller.3.This building __________(build) in

题目

By_____(do)a lot of exercise,he became stronger and taller.3.This building __________(build) in
3.This building __________(build) in 1984.
4.Mrs.Smith never ________(let) her dog ________(sleep)outside.

答案

doing 介词后面用doing
3.was built 被动语态 ,因为是1984年建造的要用过去事态的被动语态.
4.let sleep let 是使役动词,后接不带to的不定式.变被动语态时候,to要加上,这里是主动语态.无需加to.