Put the verbs in brackets in the correct form,present simple ,present continuous ,present perfect ,present perfect continuous or past simple

One of the most painful problems of our time is environmental pollution. It is dangerous because it does not know the borders of states, so pollution of land, air, seas, rivers and especially the oceans harms many countries, not just the country whose businesses are polluters of nature. That is, everyone suffers from the actions of individual states. Therefore, environmental pollution is a global problem.People need to meet their needs for food, clothing, household items. The problem is that the desire to reduce the cost of production of various goods often leads to savings on treatment plants. This leads to pollution of the environment, which has already reached alarming proportions.In my opinion, if humanity wants to continue living on our planet, it must join forces in the struggle for a clean environment. We have one planet, and if we destroy nature, we will all perish, because people are part of nature, although they often forget about it. If humanity spoils the environment, our descendants will have nowhere to live. Therefore, all countries must contribute to the cause of environmental protection.