Tom gave Helen an apple in exchange for a piece of cake.
汤姆用一个苹果和海沦换一块蛋糕。
She's always helping people.
她总是帮助别人。[现在进行时]
The currents of air that the walls of the ship direct upwards, as well as in the line of its course, are enough to give the great bird with its immense wings sufficient sustenance and progress.