1. ............ is an absolutely necessary; extremely important.

Essential

Espresso

Esquire

Estate

2. Other ............ equipment was turned off until the re-entry.

essential

nonessential

essence

essentially

3. ............ is the synonym of essential.

Inessential

Unneeded

Unnecessary

Necessary

4. ............ isn't a synonym of essential.

Vital

Unnecessary

Required

Requisite

5. Small staffs and a lack of ............ are other problems.

essent equipment

essential equipment

essention equipment

assential equipment