er to do something meaningful, it’s necessary that you _______ determine what is really important.

Alice, please tell Eric to call me when he _____ back. –No problem.

Time can never ________ from people in London the sadness and heartache caused by thoserecent terrorist attacks.

When the students heard the alarm, they all hurried to they thought was an emergency exit door

Exploring ________ space is exciting, yet dangerous.There is _______need for both robots and humans for space exploration.