Dam serduszko:)
Uzupełnij tekst odpowiednią formą have to, must, mustn’t, should.
If you feel unfit and you think you do something about it, try running. It’s easy, youcan
do it anywhere and youbuy any special equipment, except for some good running shoes. But there
are some important rules you follow. For example, you start each run with walking or
slow running to warm up. And remember, you run on hard ground because you hurt your knees.