You can only be sure of you have at present; you cannot be sure of something ___ you might get in the future.
A new product must be _________ before it comes into use.
If you find yourself ______ no one will help you, please call me.
A big earthquake hit Ludian in Yunnan, ________ many deaths and injuries and a big loss of property.
In my opinion, ________ matters is whether we can win together as a team instead of individuals.
No student ________ go out of the school campus after 10:00 at night without permission according to the school regulations.