they took the sick boy to the hospital at once改为被动语态 at once放在哪里,by them 放在哪

被动语态中by sb的位置比较灵活, The sick boy was taken to the hospital at once by them.The sick boy was taken by them to the hospital at once .两种说法都行,前者更好一些.希望能帮到你,祝你开心....