分析句子成分He thinks studying grammar is a great way to learn a l

这个句子是宾语从句.
主句是He thinks,从句是studying grammar is a great way to learn a language（是thinks的宾语）
主句主语是He,主句谓语动词是thinks
从句主语是studying grammar（这是一个动宾短语做主语）
从句谓语动词是 is,从句表语是a great way,从句定语是to learn a language（是修饰a great way）
整句话翻译就是他认为学习语法是学习语言的一种好方法.

he 主语 subject
thingks 谓语 verb
studying grammar is a great way to learn a language宾语 object
thinks后省略了that宾语从句

He是主语，thinks是谓语动词，studying grammar is a great way to learn a language是宾语从句。宾语从句的主语是studying grammar，is是系动词，a great way to learn a language是表语。