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School does prepare you for the future. School prepares you for the future because it teaches you how to become an everyday worker. Think of it this way, your boss doesn't want you slacking and not doing your work in a everyday environment. Well thats what school is an everyday environment where you complete assignments and whether you do them is up to you or not. However in a common work place if you don't do your work you end up fired, or in an almost same way you fail the class. Which if you think about it is almost like failing your job.

Steel sinks when it is put into water.  (Это научный факт, используем Present Simple и страдательный (пассивный) залог, т.к. сталь помещается (кем-то) в воду)

The soldiers are often sent parcels in the army. (Регулярное действие в настоящем Present Simple Passive. Пишу в настоящем времени, раз нет обстоятельства времени - отсылки к )

Milk goes sour when it is left for three days. (тоже факт)

She was very sad because her ring wasn't found. (Она была очень опечаленной, потому что ее кольцо не было найдено. - Past Simple Passive)

The delegation will be met at the station in an hour. (Делегация будет встречена на станции/вокзале через час. - Future Simple Passive)

They helped him and everything was done in time. (Они ему, и всё было сделано в срок. - Past Simple Passive)