1. A pirate sales the sea in search of potential victims whom he can steal from. A rover is someone who just roams (wanders/ walks around) the land. 2. Do you mean synonym? if so, theses words are good: imagine, visualize, comprehend, understand, ponder, wonder. 3. You must say the sun IN the sky. To be AMONG something there most be other things surrounding the obcet. For example, the wolf AMONG the sheep, or the house is AMONG the trees. 4.You can say both, they mean different things. Near the river means you could be walking in any direction, on any road, that is near to the river. Along the river means you are following the river's route. 5. https://learnenglish.britishcouncil.org/en/grammar-reference/modals-1