Reporters are _______ to get all facts straight, present their stories fairly and never give opinions that are objective.[ ]

There are some health problems that, when ______ in time, can become bigger ones later on.

How can I get to the island you mentioned? —You can’t get thereby swimming.

Is_____ necessary ____them to stop ________ every two hours?

下列各句中，加点词表达得体的一句是 （ ）