Помогите пожалуйста... определите в предложениях видовременные формы глаголов и укажите их инфинитив.
In 1980 the best sportsman from five continents met in Moscow.
Practical work is an essential part of University education.
Last year my friend headed the research work at the Institute.
A group of foreign students will arrive at our city in five days.
The first electronic machines appeared in 1945 in America.
We are prevent and detect crime.

Спасибо большое... =)

In 1980 the best sportsman from five continents met (Past Simple Active, to meet) in Moscow.Practical work is an essential part (Present Simple Active, to be) of University education.Last year my friend headed (Past SimpleActive, to head) the research work at the Institute.A group of foreign students will arrive (Future Simple Active, to arrive) at our city in five days.The first electronic machines appeared (Past Simple Active, to appear) in 1945 in America.We prevent and detect crime. (Present Simple Active, to prevent, to detect)