At Sam’s birthday party he had many guests, who were ________friends of his.

The president of the university has been ___ for two years.

Polar bears live      on sea ice，which they use as a platform for hunting seals

––– Do you think it's a good idea to make friends with your students?–––________, I do. I think it's a great idea.

Under criminal law, people who      carry and use large numbers of fake banknotes will be sentenced to less than three years in prison.