fill in
In the test, we had to fill in the blanks.

leave
If you don't know the answer, just leave a blank.

fire
Soldiers fired blanks into the sky.

be
go
The screen's gone blank.

remain
leave sth
I left the third column blank.

completely, entirely

be, look
Gina looked blank; then understanding dawned.

go, turn (esp. AmE)
What if my mind goes completely blank with panic?
Kevin's expression turned blank.

remain

completely, totally
studiously
His expression remained studiously blank.

Blank is used with these nouns:
ammunition, astonishment, cassette, CD, cheque, disk, DVD, expression, face, look, mask, notebook, page, paper, refusal, round, screen, sheet, space, tape, verse, wall