1 A boy was off the train today because he didn't have a ticket. 2 The government hasn't got enough soldiers to put our movement. 3 Why did you up your seat to that man? You needed it more than he did. 4 Don't be scared to say what you think. We should all speak about unfairness in society. 5 It's good to look on things that you did when you were younger.

Не изнаю тебе только идиомы с keep нужно, или другие примеры, поэтому пишу все возможные варианты. Держаться наравне с кем то (чем-то) - keep up with somebody (something); держаться в отдалении- keep off; продолжать что-то - keep on/carry on; не вмегиваится - don't get involved, don't interfere/intervene, keep out of; утаивать новости - keep news to oneself, withhold the news, hold back the news. Она старается не отставать от моды - she tries to keep up with fashion; Не ходите по траве - keep off the grass; Не вмешивайтесь в их дела - keep out of their affairs; Он утаил документы - he kept the document to himself/he withheld the documents; Мы соблюдаем старые семейные традиции - we keep/adhere to old family traditions; Уберите лекарства от детей - keep the drugs/medicine away from children; Сейчас трудно держаться на уровне с технологиями:они быстро устаревают - it's hard to keep up with technology nowadays: it outdates quickly.