I haven’t been home to see my parents for two weeks; I _______ them.

Time should be made use ______ meaningful things.

Taxi is one of the most common means of city transport, so the increase of taxi _______ in Hangzhou has led to much public concern.

—Do you know when we will carry out the plan?—Oh, no. It is still ________ discussion.

.I invited him to dinner, but he___ my invitation with thanks.