Hello! I have two questions about French grammar.
1) How to use the word “sois”? I can’t entirely understand the meaning
2) What is the difference between participe présent and participe passé?
Thank you!

Question

Answer

1) "sois" can be the verb "to be" conjugated in the imperative mode : "Sois patient!" = Be patient! 
Or : the verb "to be" conjugated in the subjonctive mode (je and tu) : "Il faut que je sois patient." = I must be patient (literally: it is necessary that I be patient) "Je veux que tu sois heureux." = I want you to be happy.

2) There are too many differences to be covered in one post. They are roughly the same as in English (ex : walking/walked).
Some examples with "marcher" (to walk) : participe présent : marchant - participe passé : marché.
- Participe présent :
ex : J'ai vu un homme marchant le long de la route. (I have seen a man walking down the road).
ex : J'apprends mes leçons en marchant. (I learn my lessons, (while) walking)

- Participe passé :
ex : J'ai marché trois kilomètres. (I've walked 3 km).

Both 'participes' can be used as adjectives. ex : coupant / coupé
- Cette lame est très coupante. (This blade is very sharp)
- Ce gâteau est coupé en parts égales. (This cake "is" cut into equal parts)
It sounds pretty akward in English, but I hope you got the French parts!

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