Quote Originally Posted by zorro View Post

There's another exercise where I need to choose the imperfective or perfective aspect. This type of exercise is in each chapter and I'm still not sure about which is which. What about this one?
Даже если они долго (search for), они Вадима не найдут. Is it поищут, the perfective?

Z
It should be the imperfective form: "даже если они долго БУДУТ ИСКАТЬ, Вадима они не найдут".

Why "БУДУТ ИСКАТЬ"?
(1) The process of searching for Vadim will be ONGOING and, probably REPEATED:
they will look here and there and everywhere;
(2) They will fail to find him, the main sentence implies that the process of search will be unsuccessful.