a subordinate clause that begins with a conjunction such as ‘although', 'while', or ‘whereas', and makes a statement that is unexpected in some way, or contrasts with information in another clause. For example in the sentence ‘I've never met my neighbours, although I've lived here for five years', the information after ‘although' seems unexpected. In the sentence ‘Men have to wear business suits to the office, whereas women can wear what they like' there is a contrast between the two clauses. 让步从句(指以although,while或whereas等开始的从句,里面包含出乎意料或与其他子句信息冲突的事实或观点)