With the mid-term examination approaching, students should ______ to stay energetic.

The system has been designed to give students quick and easy____. to the digital resources of the library. 

Come and see me whenever _______.

The lack of money forced them to________their research.

—Oh, I've just locked my keys in my office again.—You're always so careless, but ________ let's see what we can do about it.