I think _________ necessary for students to take an interest in all subjects.

If you have the chance，which dress will you choose ?—I can’t decide．Maybe the second one is _______________ the two．

Carl Linnaeus made great contributions to ________ plant species.

Is it polite to speak and laugh loudly _____? —No, I don’t think so. [ ]

The old woman kept one black dog and two white ______.