.Elephants, which are the largest mammals on the earth, have almost no natural enemies ______ human beings.
While the soldier’s idea was interesting, the system was too difficult to be ____.
In old days, books for blind people used paper ____ against metal wire to form letters.
One winter day ____, he saw the tracks of animals in the snow and observed that the appearance of each one was different.
People from the West like to use these words in cases ____ some people in Asia may not think it necessary.
The manager would like to offer the position to ____ is fit for it.