Many questions were asked，particularly ______ the cost of the new plan.

A teacher must see to it that every one of his students develops        .

This tree looks high and strong but ____ its trunk is hollow.

Nobody could believe what Chloe says because she is ______ changing her mind.

 ---I was riding along the street and all of a sudden, a car cut in and knocked me down. ---You can never be         careful in the street.