at certain degree on certain extent at和on用的对么?

at some certain time sat数学题一道at a certain high school there are 9 students on the You can declare excess valuation on certain baggage at the a 翻译at a certain 急 翻译She is not certain at first. certain 英语翻译a dedicated building on certain days. make certain of和be certain of的区别? a certain man 和 the certain man 的区别 stand a certain degree帮忙翻译阿. in和on和at的区别 on和in和at的用法?