So , a person who has trouble understanding anything ( hardly understands ) call - slow or dim , however, it is worth remembering that they are usually soften putting ahead a bit , or rather.

Her husbands a bit dim.

My students were rather slow.

Of students who study with things are not going , they will say that he struggle

My daughter struggles with maths. Shes struggling at school.

The following statement has more offensive and is used to say "a person without a hint of intelligence » - a vacuous expression (vacuous [ vækjuəs] - meaningless , empty