on the basis of 根据…, 在…基础上
in brief(=in as few wordsas possible)简言之
be certain of (=be sureof) 有把握, 一定
for certain of (=for sure)肯定地,有把握地
by chance(=accidentally,by accident)偶然
attach(to) (=to fix,fasten; join) 缚, 系 ,结
make an attempt at doingsth. (to do sth.) 试图做…
attribute…to…(=to believe sth. to be the result of…)把...归因于..., 认为...是...的结果