ПРоверьте, пожалуйста, правильноли сделала английский. Заранее благодарна.

Непонятно, с какого на какой язык перевод делался. Поэтому, только грамматику подправляю.. .
• Everything was arranged in good time. - Все было организовано ВОВРЕМЯ. Past Indefinite, PASSIVE voice.
• The problem will be solved in the near future. - Проблема будет решена в ближайшем будущем. Future Indefinite, PASSIVE voice.
• The mail has just been sent off. – Письмо было ТОЛЬКО ЧТО отправлено. PRESENT PERFECT, Passive voice.
• When we came to the factory, the new equipment was still being installed. - Когда мы пришли на фабрику, новое оборудование все еще установливали. PAST CONTINUOUS, Passive voice.
• The meeting has been put off. - Заседание ОТЛОЖЕНО. PRESENT PERFECT, Passive voice.
• The question was asked several times. – Вопрос был задан несколько раз. Past Indefinite, Passive voice.

В третьем перевод мне кажется лучше сказать: письмо только что оправили, там не сказано кому и уточняется "только что" наверное и время другое будет.

•The problem will be solved in the near future. - Passive voice.
•The mail has just been sent off. (тут нету "Вам", зато есть just). – Письмо только что было отправлено. Past perfect
•When we came to the factory, the new equipment was still being installed. -
сложное предложение. Первое - Past Indefinite, Active voice. Второе Past Cont., Passive voice.
•The meeting has been put off. - Past Perf.

All has been arranged in time. - All has been organised in due time. By Uncertain, the Active voice.
• the Problem will be solved in the near future. - the problem will be solved in the near future. Future Uncertain, the Active voice.
• Mail has been just sent. – the letter has been sent you. By Uncertain, the Passive Voice.
• When we have arrived to the factory, the new equipment was still established. - when we have come on the factory, the new equipment still установливали. Existing Uncertain, the Passive Voice.
• the Meeting has been postponed. - session has been postponed. By Uncertain, the Passive Voice.
• the Question have set some times. – the question has been set some times. By Uncertain, the Passive Voice.