وقتی که مطمئن هستیمIt’s highly unlikely that we’ll be able to prevent the Arctic ice from melting. There’s little doubt that the climate is changing. I very much doubt that we shall be able to reverse the process of global warming. There’s every (strong) likelihood that man will return to the Moon in the near future. Space travel is bound to continue. It’s very probable (possible) that tigers will become extinct in the wild.