先分析整个大句子的成分：
We 是整个主句的主语
think 是整个主句的谓语
it is very important that we should master at least one foreign language.是整个主句的省略that引导词的宾语从句
在分析宾语从句中的语法现象：
这是it在做形式主语 真正的主语是that we should master at least one foreign language 先分析整个大句子的成分：
We 是整个主句的主语
think 是整个主句的谓语
it is very important that we should master at least one foreign language.是整个主句的省略that引导词的宾语从句
在分析宾语从句中的语法现象：
这是it在做形式主语 真正的主语是that we should master at least one foreign language