.Among all the problems,_______is so difficult as this one.
A.not one B.either C.neither D.none
It was 1920 ______ regular radio broadcasts began.
A.while B.when C.that D.since
_____ is reported in the newspaper that talks between the two countries are making progress.
A. Which B. As C. That D. It
Have you any knives？ I need a sharp ________.
A.it B. another C. one D.any
Lucy has a great sense of humour and always keeps her colleagues with her stories.
A. amused B. amusing C. to amuse D. to be amused
Every few years, the coal workers their lungs X-rayed to ensure their health.
A. are having B. have C. have had D. had had
