كَان : (( كان ذالك في الكتاب مسطورا)) يَكونُ:يكون المسلم مؤدباً كُنْ:كُن مؤدباً كُوْني :كُوني كال كالشجرة كَيْنُونة: كان : in the past يَكُونُ : in the present كُن : in the order this is the verb كان but which is the with verb to :be is not mentioned in Arabic , `Mohahamed is a good person : we said : محمد إنسان جيد and we did not say : محمد يكون إنسان جيد

The weather will be good. سيكون الطقس جميل I guess this is quite right. x)

We don't normally use it. If you're thinking about the verb "be" we don't have (I "am" a student) in Arabic it's like (I student) We normally use that very "يكون" when we are saying "become" For example يكون الطالب ناجحاً، إذا درس بجد The student becomes successful, if he studied hard.

The answer is like what they said in comments. There's no to be in arabic like english . I am haapy in arabic we say as i happy انا سعيد ولا نقول انا اكون سعيد ....verb يكون in future is او سيكون سوف يكون ..in past كان ..in present يكون ..in order is كن we remove in order the litter و ...we almost use verb يكون as verb to be in english when we are talking about state in future ,past ، and sometimes in order but not present ..e.g i was happy انا كنت سعيد ..i will be okay سأكون بخير ( او ) سوف أكون بخير ...be happy كن سعيد ...and if i wana say i am not happy we don't usually use يكون like انا لا أكون سعيد ..it's right but not usually be used we say instead ..أنا لست سعيد ..Wish u more progress in Arabic :)

كان =was (singular) or were (plural) like : كان الولد هنا =the boy was hereا كان الاولاد هنا=the boye were here. يكون= present ولكن نضع معها س مثل سيكون هاذا الطالب عظيما. او سوف يكون هاذا الطالب عظيما . كن =be To give an order like Be a good student=كن طالب جيد