Подскажите ! по -в каких случиях must пишется, а в каких mustn't? зарание !

Долг, обязанность,  настоятельный  совет или какую-либо необходимость. в данном случае перевод будет звучать так: должен, обязан. если мы используем конструкцию i must — значит, мы берем на себя долг и обязательство, которое должно быть выполнено по моральным принципам, чтобы совесть была чиста. you must tell your mother everything what you have done. — ты обязан рассказать маме все, что ты сделал. i must learn english because i have a strong desire to live better. — я должен учить , потому что я хочу лучшей жизни. they must leave us.   - они обязаны покинуть нас. every young man must serve in the army. — каждый юноша обязан  служить в армии. 2. модальный глагол  must + not (mustn’t) используется как запрет. в данном случае мы переведем: нельзя, не должен.  именно  такая форма передает строгость подчинения приказаниям, которую можно  приравнять  к соблюдению закона, подчинению правилам. you mustn’t disturb your father. he is ill. — ты не должен  беспокоить  отца. он болен. you mustn’t be so careless. — ты не должен быть таким  безответственным. you mustn’t speak like that with your parents. — ты не должен так разговаривать со своими родителями. you mustn’t miss your english lectures. — ты не должен пропускать лекции по .

You can see david in the first photo. he ..is .speaking   on his mobile phote. he often ..phones home to learn about his puppy's latest adventures.   there are two girls in the second photo. sue and indira .are ..smiling. they are nice and friendly. in the evening, they .. different dishes from their countries. yesterday, i tasted an indian one. it was spicy,but delicious!   look at marko! he ..is football.he . well. he is really good at football.   emily, from great britain, . to become a journalist,in the photo, she .is.. an article about out explorers' club.   now just look at the photos! jessica ..is an english magazine for explorers and andrew .is ..feeding a squirrel in the park.   sorry, but i have to finish my e-mail. our english lesson will begin in 5 minutes.     best wishes,

Iagree with this statement. a man often thinks about himself: "i'm so stupid”, or "i am so fat", or ‘i am a looser! ”. he is sure that he’s not worthy of being loved by anyone. other people are treating him badly or unfair. why? i can answer you: people treat him badly because he treats himself badly! it's as simple as that.  why would any men or women love or respect him when he   doesn't love and respect himself? you must change yourself and your way of thinking. we must change our thoughts about ourselves! we must think positively: “i am cool”, “that was really clever of me to do it that way”, “i look really nice”, “i can do anything i really want to do” and most important of all; “i am worthy of loving myself! ”. once you love yourself, and treat yourself with respect other people will love you and treat you with respect too.