As is the custom, police forensic experts carried out a painstaking search of the debris.
像往常一样，警方的.法医专家对残骸进行了仔细的查看。
The mastery of a language requires/ needs painstaking effort.
要学好一种语言，必须下苦工夫。
I don't know how to make polite conversation.
我不晓得怎么说应酬话。
He had always been polite ─ she couldn't fault him on that.
他总是彬彬有礼——她在这方面对他无可指摘。