例句：
Certain of those present were unwilling to discuss the matter further.
某些在場的人不愿意進一步討論這個問題。
Those beliefs still prevail among certain social groups.
這些信念在某些社會群體中仍很盛行。
The work must be completed within a certain time limit.
這項工作必須在一定期限內完成。
The company's financial position is not certain.
這家公司的財務狀況不明朗。
Many animals breed only at certain times of the year.
很多動物只在一年的某個時候繁殖。