例句：

　　Certain of those present were unwilling to discuss the matter further.

　　某些在場(chǎng)的人不愿意進(jìn)一步討論這個(gè)問(wèn)題。

　　Those beliefs still prevail among certain social groups.

　　這些信念在某些社會(huì)群體中仍很盛行。

　　The work must be completed within a certain time limit.

　　這項(xiàng)工作必須在一定期限內(nèi)完成。

　　The company's financial position is not certain.

　　這家公司的財(cái)務(wù)狀況不明朗。

　　Many animals breed only at certain times of the year.

　　很多動(dòng)物只在一年的某個(gè)時(shí)候繁殖。