I kept the engine running because it might be necessary to leave fast...
We will do whatever is necessary to stop them...
Is that really necessary?...
Make the necessary arrangements.
Wastage was no doubt a necessary consequence of war...
Scientific work is differentiated from art by its necessary connection with the idea of progress.
...a small parcel of necessaries tied up in a handkerchief and carried on a stick.
If necessary, the airship can stay up there for days to keep out of danger...
The army needs men who are willing to fight, when necessary...
All the rigging had been examined, and renewed where necessary.