speaking english in class in useful的主谓宾是什么

speaking english in class in useful的主谓宾是什么
speaking english in class in useful的主谓宾是什么

speaking english in class in useful的主谓宾是什么
speaking english in class is useful
主 speaking english
系 is
表 useful

句子应该是：Speaking English in class is useful.
如果是这样的句子，则：
主语：speaking english
谓语：is
宾语：useful