What happened to you?—- I ________ in the street when someone patted me on the shoulder, which frightened me

It’s important ______ the piano well.

A sense of __________ is the basic requirement for people working in the service industry, such as education and health care.

He doesn’t have any money, _______ do I.

All __________ people on the earth should use the natural resources wisely， or they __________ by the nature sooner or later.