Some insects ______ the colour of their surroundings to protect themselves.

Lucy has _____ all of the goals she set for herself in high school and is ready for new challenges at university.

In the time of HINI, scientists ____ their spare time to conduct research on the ways of curing the disease.

The socks are so ______ that they can't be mended any more.

As an Olympic volunteer，you should know how to ________ emergent cases.