Unless as long as in case

If you don't train hard, you won't succeed in sport. You [blank_start]won’t[blank_end] succeed in sport [blank_start]unless[blank_end] you [blank_start]train[blank_end] hard.

If you train regularly, you can improve your performance. You [blank_start]can[blank_end] improve your performance [blank_start]as long as[blank_end] you [blank_start]train[blank_end] regularly

Take a spare pair of running shoes, because it's possible that you will need them. [blank_start]Take[blank_end] a spare pair of running shoes [blank_start]in case[blank_end] you [blank_start]need[blank_end] them.

We’ll go for a picnic by the river tomorrow if it doesn’t rain. [blank_start]Unless[blank_end] it [blank_start]rains[blank_end], [blank_start]we’ll[blank_end] go for a picnic by the river tomorrow.

If you enjoy your sport, it doesn't really matter whether you succeed or not. It [blank_start]doesn't[blank_end] really matter whether you succeed or not [blank_start]as long as[blank_end] you [blank_start]enjoy[blank_end] your sport.

Take a waterproof coat with you because It's possible that It will rain. [blank_start]Take[blank_end] a waterproof coat with you [blank_start]in case[blank_end] it [blank_start]rains.[blank_end]

If you don't eat and sleep properly you won't develop as an athlete. You [blank_start]won't[blank_end] develop as an athlete [blank_start]unless[blank_end] you [blank_start]eat and sleep[blank_end] properly.

Take a first-aid kit because it's possible that someone will get injured. [blank_start]Take[blank_end] a first-aid kit [blank_start]in case[blank_end] someone [blank_start]gets[blank_end] injured.