Объяснение:
If we are only talking about crossing the ocean, then personally I would have swum it three times. For example, if you start from a point in Eurasia, you can go to Africa without crossing the ocean. From Africa to cross the ocean for the first time to Australia. Then swim a second time and visit Antarctica. From Antarctica we are sailing to South America for the third time. And from there, through the Panama Canal, we get to the North.
If you wish, you can and only once swim across, given that Australia and Antarctica, like Antarctica and South America, are separated not by oceans, but by bays and seas.
Эти хвостики называются "апострОфами". В данном случае won't расшивровывается как will not, isn't как is not и так далее. Обычно используются для сокращения.