As is the custom, police forensic experts carried out a painstaking search of the debris.

　　像往常一樣，警方的.法醫(yī)專(zhuān)家對(duì)殘骸進(jìn)行了仔細(xì)的查看。

　　The mastery of a language requires/ needs painstaking effort.

　　要學(xué)好一種語(yǔ)言，必須下苦工夫。

　　I don't know how to make polite conversation.

　　我不曉得怎么說(shuō)應(yīng)酬話。

　　He had always been polite ─ she couldn't fault him on that.

　　他總是彬彬有禮——她在這方面對(duì)他無(wú)可指摘。