а) В первой бригаде на 3 человека меньше, чем во второй , а во второй бригаде на 5 человек больше, чем а третьей. Сколько человек в каждой бригаде , если во всех трёх 52 человека?

б) На второй полке книг на 5 больше , чем на первой , но на 5 меньше, чем на третьей . Всего на полках 105 книг. Сколько книг на каждой полке?

Вычислите объемную долю угарного газа в образце воздуха,в котором предельно допустимая концентрация (ПДК)угарного газа превышена в 3 раза. ПДК(СО)=0,02 мг/л

(1) Use Present Perfect or Present Perfect Continuous:: 1) I can' t believe that it (be) only three years since I met you. 2)"How long you (be) here?" Тоm demanded quietly. 3) We (not meet) Katya for а long time. Не (change) very much? 4) Listen to те, all of you. I (come) with the most terrific news. 5) This flat is just what I (look for). 6) I trust you. After all I (know) you all ту life. 7) I want you to remember that I never (ask) you for anything before. 8) Ivan (go) to Europe for а holiday. I myself never (be) there. 9) What' s that noise? — Vasya (break) а vase. 10) I (not wear) this coat for two years. 11) I’т so tired. I (clean) ту room since morning. (2) Will be doing or will have done? Make sentences with will be -ing and will have done. 1) Tomorrow Jean is going to swim from 1 о'clock until 3 о'clock. So, at 2 о'clock she ___________________________ 2) I’m going to watch а film from 8 о'clock until 11 о'clock this evening. So at 9.30 I ___________________________ 3) Му father is going to repair the car tomorrow morning from 7 о'clock until 8.45. Sо at 7.30 he ___________________ 4) I always go to school at 8 о'clock. So, at 9.30 in the morning tomorrow I ________________________ 5) Tim’s classes end at 1.30. So at 3 о'clock when mother comes to school Tim's classes ________________________ 6) We' re going to the theatre. The play begins at 5.30. So, at 6.00 when I reach the theatre the play ____________________