4. Choose the correct variant. a) My fathers advice are useful.
b) My father's advices are useful.
c) My father's advice is useful.
d) My fathers' advice is useful.​

Переведем 1,2 м/с в м/ч.если в 1 часе 3600 секунд,то: 1,2*3600=4320 метров в час.за 3,8 часа он пройдёт 16416 метров. (3,8*4320) теперь сделаем тоже самое с 0,9 м/с 0,9*3600=3240 метров в час.за 2,2 часа он пройдёт 7128 метров. (2,2*3240) всего он прошёл 23544 метра (16416+7128)  за 6 часов (3,8+2,2). его средняя скорость была: 23544/6=3924 метров в час.если переводить в м/с,то: 3924/3600=1,09 м/с ответ: 1,09 м/с p.s.вообще можно было решить быстрее: 3,8*1,2+2,2*0,9 / 6 = 1,09 (м/с) давно закончил школу и не уверен,что правильно будет перемножать "часы" и  "секунды",хотя ответ получится одинаковым.

Opening of mikhail lomonosov had enriched many branches of knowledge. developed the atomic-molecular understanding of the structure of matter. during the rule of the theory of calorie argued that the heat caused by the motion of the particles. formulated the principle of conservation of matter and motion. excluded the phlogiston from among the chemical agents. laid the foundations of physical chemistry. studied the atmospheric electricity and gravity. he put forward the theory of color. created a number of optical devices. opened the atmosphere at venereal lomonosov was born on november 19, 1711, in the village denisovka (now lomonosovo settlement) in the family of pomor. in 19 years left to go to school (1731 at the slavonic-greek-latin academy in moscow from 1735 at the academic university in st. petersburg, in 1736-41 in germany). from 1742 associate with 1745 academician of the petersburg academy of sciences.