将一个磁性材料放于加有磁化力（H）的区域中时，材料中的磁感应强度（B）是以哪种方式产生的？

The students in our school each ___ an English dictionary.

The students in our school each ___ an English dictionary.

The students in our school each ___ an English dictionary.

If I had known that, I ___ so.

My father, together with some of his old friends, ___ there already.

My father, together with some of his old friends, ___ there already.

My father, together with some of his old friends, ___ there already.

My father, together with some of his old friends, ___ there already.

My father, together with some of his old friends, ___ there already.

My father, together with some of his old friends, ___ there already.