Вам даны слова: take place,run (3),be(5) compete! после слов такие цифры! это значит это слово столько раз повторяется! текст: in march 1981,the first london marathon . 7,747 people in it. so,people the london marathom since 1981. ,195 kilometrovs long.

In march 1981,the first London Marathon took place . 7,747 people competed in it. So,people have been running the London Marathom since 1981. it is 42,195 kilometrovs long.

думаю так

In march 1981,the first London Marathon TOOK PLACE . 7,747 people COMPETED  in it. So,people  HAVE BEEN RUNNING the London Marathom since 1981. it IS  42,195 kilometrovs long.

ЦИФРЫ ПОСЛЕ СЛОВ ОБОЗНАЧАЮТ НОМЕР ПРЕДЛОЖЕНИЯ!