We use For when we measure the duration – when we say how long something lasts. I have known her for a long time. don't use For with expressions such as all day or all the time. "I was there all day." not "I was there for all the day." we can use all verb tenses with For.

These words are prepositions and yes, they can be difficult to use. Any preposition can be used in the context of what you can do to a box. You can stand on a box, with a box, by a box, etc. Here are some examples that may help! ON: Standing on something. Usually used when describing where you are. An example would be "I am on the bridge." You are positioned on top of it. BY/WITH/FROM: All are a part of the ablative case. "by" is used in many ways, like "The dress was made by me" or "she's standing by me." Preposition with can show accompaniment, like "I walked with Sally." AT: Is part of the accusative case and is used in conjunction with a direct object to describe the time in which something is occurring or the place in which something is occurring. "The plane will land at 12 o'clock" or "I will meet you at the station". TO/FOR: Are part of the dative case and are taken with an indirect object, such as "I bought the book for you". Book is the accusative direct object of the verb, but the dative indirect object accompanied with the preposition "for" further describes the action. The main purpose of prepositions are to further describe the actions and once your English improves it will come more naturally. My knowledge of Latin really helped me with my English grammar. Good luck!

Prepositions of Time: at, in, on We use: at for a PRECISE TIME in for MONTHS, YEARS, CENTURIES and LONG PERIODS on for DAYS and DATES Example: at 10.15 am in summer, in may, in 1990 on Wednesdays, on my birthday