3. mendeleev noticed that elements had repeating patterns, or
are
with properties such as melting
point,
-, and

Answer erosion,oil spills,pollution,tourism,urban development;

The first immigrants to settle in what is now the united states were the ancient ancestors of modern native americans. the precise routes of those first north american immigrants are disputed, but there is no uncertainty about the fact that every human being on the continent is either a recent immigrant or a descendant of earlier immigrants. since the first immigrants came here from asia more than thirteen thousand years ago, there have been four large and easily recognizable modern waves of immigrants into the united states.

Answer is b)eutrophication occurs when excess nutrients are present in aquatic ecosystems, resulting in the increased production of plant life and the subsequent decrease in the oxygen levels of the watereutrophication occurs when there are excess nutrients in a body of water. this results in plants having more food and reproducing  more, sometimes leading to more aquatic animal life as well. ultimately, this can reduce the oxygen level in the ecosystem. 

Many foreign companies buy/build hotels in areas therefore most of the profit from tourism goes to these companies rather than the local economy or local people. 
also, these foreign companies might only employ foreign workers with experience meaning they receive more pay whereas local people would be employed for low skilled jobs and lower pay. 

thats all i can think hope it : )