——Is it my appearance the professor minds?——I guess not. He will consider necessary to have an experienced assistant.
The police __________ searching for the murderer everywhere when he suddenly appeared in a theatre.
Experiments of this kind __________ in both the U. S. and Europe well before the Second World War started.
After the explosion, every means __________ prevent the river from __________.
We students should __________ ourselves __________ knowledge, for the competition nowadays is very fierce.
He is really considering __________ himself to __________ these children of the poor mountain village.