你那句有错
宾语从句
he found (that) it is very difficult to learn maths
it是形式主语,带的to learn maths,主语太长,所以要指代
to learn maths is very difficult
你那句有错
宾语从句
he found (that) it is very difficult to learn maths
it是形式主语,带的to learn maths,主语太长,所以要指代
to learn maths is very difficult