с англ, кто хорошо знает Open the brackets and put the verb into Simple or Progressive tenses
12) Without human interference, air and water (renew) themselves. 13) Tomorrow we (analyze) this phenomenon for the whole morning. 14) Human activity (influence) the global environment. 15) In his first article D.I. Mendeleyev (point out) the similarities of a number of properties of certain elements. 16) Stars like the Sun (convert) hydrogen and helium into carbon, oxygen, nitrogen, magnesium and iron. 17) For the whole last century, modern botany (develop) rapidly. 18) Scientists report that the concentration of carbon dioxide in the atmosphere gradually (increase).
