They live in a house that was built in 1990.要求省略that.
问题描述：
They live in a house that was built in 1990.要求省略that.
我的回答：they live in a house was bulit in 1990.
但是答案是：they live in a house bulit in 1990.为什么?
答
这里主要是省略了（that was）,通过分析我们知道（that was built in 1990）做的是定语修饰House,而在这样一种形式下,that was 可以省略.
按你的改法,一个句子就有两个谓语,且时态不同,这是不允许的