__________ this is true in theory, it's very different in practice.
exit
—The hall___ for international conferences is of great importance.—I see, and we are sure to complete it on time.
Since Tom ___downloaded a virus into his computer, he can not open the file now.
Seeing that the drowning child was struggling in the icy water, the soldier dived into the river without hesitation, ___ his own safety.
If you just spend your time___ gains and losses, maybe you'll get nothing in the end.