Good point Elena:

Some  synonyms for ENSURE are:

 guarantee,  assure,    establish,  protect.  provide, secure, certify,   confirm.

   I will  turn in my papers  to   ensure  that I fulfill the assignment.

   I have a  guarantee from the business  to ensure that I have faith in their product.

   An agreement can be signed to ensure that all parties  understand the specific contract.

   I will use an Alarm Clock to ensure that I can keep my appointment.

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Frankly, It is hardly to ensure that any evidence that will be occur in the few next seconds.