主要表示从某物的表面  “横过”,涉及“面”的概念.常指从这一边到另一边  1.The  bus  is  coming  across  the  bridge. 2.They  often  go  to  school  across  the  street. 3.Can  you  swim  across  the  river  而through为在立体空间中的“穿过”.物体内部穿过  如：go  through  the  forest“穿过森林”,
swim ( ) the river 是填across还是through?