Потому что это герундий. Иногда перед герундием может стоять предлог, в данном случае "by playing" означает "проигрывая" (деепричастие) или "путем проигрывания".
<span>In schools many subjects are interesting. But many students like only some of them. As for me, o</span>f all school subjects I very love physics. It's very interesting. I love to solve tasks and learn new formulas. I also like math. I love science associated with numbers, because for me they are very easy.
Как тебя зовут на какое имя и фамилию составлять портфолио????
1 did she listen to music last evening
2 did pupils write tests yesterday
3 did Tim live in the country two years ago
4 did we put our books on the table
5 did Jane see birds in the garden