2. She ____ (has taken / took) part in studying the problem last week.

Решение:

Оборот 'last week' (на прошлой неделе) указывает на конкретное время в прошлом, что требует использования Past Simple.

1. She took (has taken / took) part in studying the problem last week.

Ответ: She took part in studying the problem last week.