by accident偶然
on account of… 因为…,由于…
in addition to… 除…之外
on (the/an) average 平均,一般来说
on the basis of… 根据…,在…的基础上
at (the) best充其量,至多
on business因公,因事
in any case无论如何,总之
in case of… 假使…,万一…
in case假如,以防(万一)免得
in no case决不
by chance 偶然,碰巧
in charge of… 负责…,主管…
in common共用,共有,共同
in conclusion 最后,总之
on condition that在…条件下
in connection with/to… 关于…
in consequence 因此,结果
in consequence of… 由于…的缘故
on the contrary 反之,正相反