be deep in thought

沉思

be charitable to, be civil to, be clear about, be close to, be committed to doing sth., be comparable to, be comparable with, be composed of, be concerned about, be concerned with, be confronted with, be connected to, be conscious of, be considerate of, be considerate of..., be content with, be contrary to, be convinced that, be covered with, be crazy about, be deserving of, be detached from, be different from, be disagreeable to, be disgusted with, be doubled up, be due, be due to, be eager for sth., be eager to, be envious of, be equal to, be essential to, be exposed to, be faced with, be familiar to, be familiar with, be far from, be favourable to, be fed up,