Ответ:
1) John (tripped) and (cut) his knee as he (was walking) up the volcano.
2) Martin (hasn't reached) the crater yet.
3) Look at the volcano. Huge rocks (are exploding) out of the crater.
4) They (are going) volcano surfing tomorrow.
5) Luke (has worked) hard for the last three weeks.
6) We (are leaving) for Chile next Monday.
Объяснение: