8. The baseball player (hit) ________ the ball out of the stadium yesterday. He (hit) ________ a lot of homeruns since he (join) ________ our team.

For the first blank, we need the past simple because of 'yesterday' so the past simple of 'hit' is 'hit'. For the second blank, we need the present perfect because of 'since' which is 'has hit'. The third blank needs a past simple of 'join' because of 'since' therefore it is 'joined'. Therefore the answer is: 8. The baseball player hit the ball out of the stadium yesterday. He has hit a lot of homeruns since he joined our team.