across的基本意思是“翻过去”,可译为：过,跨越,在对面.还可表示“在...上”,如：
She found her clothes lying across the chair.她发现她的衣服平放在椅子上.
An enormous grin spread across his face.一个灿烂的笑容绽开在他的脸上.
祝进步!