关于定语从句省略that问题

题目

关于定语从句省略that问题
定语从句中that作宾语时可以被省略,那么对下面两句话进行修改：
with more of the amino acids that is essential to the human diet. ——with more of the amino acids essential to the human diet.
He completes a project that brings many benefits
—— He completes a project brings many benefits
上述这两句改动后是否正确,如不正确,错在哪?
不对，是我搞错了。不好意思

答案

改动是错误的.
定语从句中that作宾语时可以被省略,而作主语时不可以省略.上两句中,that都在定语从句中作主语,故不可省略.