Once upon a time，a(n)________famous scientist said that life was not easy for any of us but first of all we should believe in ourselves.

Scientists have shown that there is a connection ____ cigarette smoking and certain diseases

The two children，whose parents passed away，______to a life at hardship.[ ]

They _____ building the new hotel because of the greatcost.

Never _____ forget the days when _____ together with you.