1a) Martin admits that he (hit) the other car, but did not damage it.
1b) Martin admitted that he had hit the other car, but had not damaged it.
2 )"Have you (not seen) your aunt recently?" - "No, she (has not been) out of her house since we (bought) her colour TV."
3) The runner Amos Temila (broke) the world record for the 1500 metres in Frankfurt. Two days later in Helsinki, Lee Williams (ran) it in an even faster time.