При нагревании воды в закрытой пробкой пробирке увеличивается количество пара, находящегося под пробкой, и повышается его давление на пробку. Наконец, давление пара выталкивает пробку, при этом пар совершает работу. Часть первоначальной энергии пара пошло на совершение работы по выталкиванию пробки. Внутренняя энергия пара превратилась в механическую энергию.
<span>Так как пар выходит еще достаточно горячий, то оставшуюся энергию он отдает окружающему воздуху, имеющему более низкую температуру.</span>
You must test toys before you give them to your children. You must throw away the package. You must throw away long ribbons. You mustn't let small children play alone. You mustn't leave metal toys outside. You must avoid toxic toys.
1.i smoked 20 cigarettes yesterday
2.how many cigarettes have you smoked today?
3.I have been ill twice so far this year
4.how many times were you ill last year
5.I haven't drunk any coffe so far today
6.He has been late three times this week
7.
8.
9.she has red three papers and 2 magazines already
10.How many books did she read last month?
Life in the city is way noisier and unfriendlier than in the country. Life in the country is cheaper and slower than in the city. Life in the city is faster and dirtier than in the country. The city is bigger than the country.
<span>My mother is a teacher.</span>
<span>They are brothers.</span>
<span>A cat is big.</span>
<span>I go to the swimmibg pool every week .</span>
<span>She often reads.</span>
<span>She seldom watches TV.</span>
<span>She doesn't go to the swimming pool every week .</span>