This is an important problem _______ too few social scientists have researched.

He said that the group ________ him a letter and asked him to go there for an interview.

If you are walking away from a clock tower ，you will hear the ticking of the clock fade to a point ________ it cannot be heard.

I don ’t mind _______ the decision as long as it is not too late.

Hesaidthatthegroup________himaletterandaskedhimtogothereforaninterview.