happen again再次發(fā)生;
happen commonly通常發(fā)生;
happen easily容易發(fā)生;
happen frequently經(jīng)常發(fā)生;
happen historically在歷史上發(fā)生;
happen lately最近發(fā)生;
happen logically合乎邏輯地發(fā)生;
happen mysteriously神秘地偶然發(fā)生;
happen opportunely恰好出現(xiàn);
happen promptly很快地發(fā)生;
happen spontaneously自發(fā);
happen subsequently隨后發(fā)生;
happen usually通常發(fā)生;
happen along偶然出現(xiàn),碰巧來到