Выберите правильную временную форму (Present Perfect or Past Simple): 1. He was (interested / has been interested) in scientific research since he entered the university. 2. When did you (install / have you installed) the new equipment in the laboratory? 3. They (didn't give / haven't given) the explanation of these strange facts yet. 4. They (determined / have determined ) the main properties of the substance. 5. He (has just made / just made) a discovety in physics. 6.They (didn't receive / haven't received ) any good results when they worked with this type of equipment.