求问句子结构及意思。I don't understand it.
Litter enters the seas from both land-based sources, from ships and other installations
at sea, from point and diffuse sources。
what does does this sentence mean in Chinese？And what is the structure of it？谁英文好能帮忙解释下么，谢谢。And thanks very much.

Question

求问句子结构及意思。I don't understand it.
Litter enters the seas from both land-based sources, from ships and other installations 
at sea, from point and diffuse sources。
what does does this sentence mean in Chinese？And what is the structure of it？谁英文好能帮忙解释下么，谢谢。And thanks very much.

Answer

大量的垃圾从各种陆地上，船和人造平台直入大海。 From point and diffuse sources just means "all kinds of entry points"

Answer

It is explaining WHERE litter comes from. Land, ships and other things IN the ocean. It comes FROM the point (a harbor, a ship, a dock, an oil rig) and DIFFUSES (melts into the sea, spreads through the water) out into the ocean.

I know this is an English explanation, but I will try to explain it in Chinese in another comment! :)