Complete the text with suitable prepositions:— Trees are very useful (a)——- man. They are highly essential (b) —— our existence. They protect the rich top soil (c)—— getting washed away (d) ——-- rain water and floods. We can see trees being grown along the mountain slopes, (e) ——- the road sides, (f) ——-- the parks and gardens. They add beauty (g) ——- our lives. They provide us (h)———— food, wood, shade, shelter and so on. They take (i)——- carbon di-oxide and produce oxygen. So we should take care (j) ———- trees.