Example : He verified that the valves were closed.
See that the curtains are closed.
Control the quality of the product.

Synonyms : ascertain, assure, check, control, ensure, see, see to it

Example : This nest egg will ensure a nice retirement for us.
Preparation will guarantee success!.

Synonyms : assure, ensure, guarantee, secure

Example : The insurance won't cover this.

Synonyms : cover, underwrite