Two middle-aged passengers fell into the sea____, neither of them could swim.
There is a limit __________ people's life, but no limit __________ the knowledge.
Unfortunately, the research was limited __________ increasing economic profits,__________ protecting the environment.
They are trying to find a new way to __________ the spread of AIDS.
They will have you __________ if you don't pay taxes, because it is everyone's duty to pay taxes.
She was __________ for helping the murderer to escape.