It’s high time that we students________ harder as theexamination is drawing nearer.

I____thesaxophoneatregularintervals(间隔)formanyyearswhenIwasachild.[ ]

Many students are ________ chatting online, which wastes them plenty of time.

right in the center of the city, the park attracts a lot of tourists.

The ________ reminded me of a snow night twenty years before.