You can’t imagine what great trouble they have _____ the problem _____.
Swimmers must be very strong in order to build up speed because of the high resistance of the water. Runners, ____, must struggle against the heavy resistance of the air and ground.
To read newspaper before going to bed seemed to me a rule ____.
It's no secret to us, but he alone is in the dark. It means ____.
Every year, ____ graduates take pan in TOEFL for further education abroad.
In order to ____ the debt, the couple has worked hard for years with little food and only a small room to live in and never a moment's rest.