Не или ни? Докажи своё мнение.
Пример:
«Н_ раз он пожалел о сказанном». Пишем не, потому что можно заменить: много раз.

«Н_ разу не пришлось объяснять эту тему дважды». Пишем ни, потому что можно заменить: никогда.
Ты н_ разу не опоздал в школу.
=
много раз
никогда

Open the brackets and put the verbs into the Future Indefinite, the Future Perfect, the Present Indefinite or the Present Perfect Tense. 1. By 8 o'clock they (have) dinner. 2. By the end of the week he (finish) the translation. 3, Before you (come) I (do) all the work. 4, She (look) through the article by 12 o'clock. 5. They (receive) our letter by Monday. 6. By the time we (get) to the forest the rain (stop), 7.1 think he (answer) the letter by this time. 8. We (begin) to work after we (read) all the instructions, 9, We (not do) anything until he (take) necessary steps. 10. The committee (prepare) the plan by tomorrow. 11.1 suppose when my letter (reach) you I already (return) from your voyage, 12. He (pass) an exam after he (learn) all the material. 13.1 am afraid they (not discuss) all the questions by the time they (come). 14. We (not be able) to start the experiment before we (obtain) the necessary data. 15. The secretary already (look) through all the papers before the boss (come). 16. My train (leave) by the time you (come) to the station.