以下是几组比较好的定义。
"Concessive clauses indicate that the situation in the matrix clause is contrary to expectation in the light of what is said in the concessive clause" (A ComprehensiveGrammar of the English Language, 1985).
让步状语从句表示：我们根据从句内容会产生一个预期，但是主句内容却与它相反。
例如：Thoughhe has tried his best, he lostthe game.（从句“尽了最大努力”，预期应该是胜出；但结果却与之相反：他输了比赛）
Concessive clauses are adverbial clauses, so called because they admit or concede something, in spite of which the statement made in the main clause is and continues to be true. The truth of the main clause is being emphasized by contrast.
从句中承认某种相反看法，但尽管有这个认可，并不影响主句陈述内容的正确性。事实上，主句陈述的正确性，正是通过这种对照得到了强调。
例如：We thoroughly understand each other, even if we don’t always agree.（彼此存在分歧，这是一个事实；但这并不影响我们互相理解对方。这句话恰恰是通过“分歧”来突出“理解”）
Concessive construction is another type of contrast, where the idea of one clause is in some way opposing the idea of the other, and which often expresses an element of surprise. For example, we may feel that it is surprising to pay a lot of money for a meal in a restaurant and to find that the food is awful, or to fail an exam after studying hard.
让步结构也是一种对比。从句内容与主句内容存在某种相反关系，主句呈现给我们的往往是预料之外的。例如：（虽然）我们发现餐馆饭菜很糟糕，却要付很多钱；（虽然）学习很努力，考试却没通过——后面主句的结果都是有些出乎意料（surprising）的。
因此我们可以得出这样一个结论：
让步状语从句的话题，是给主句做铺垫，为的是引出一个全新的、不同的话题。
简单一点理解，是否可以这样说：如果把though从句连词换成because，主句改为否定，从句和主句就可能是因果关系？
例如：
Thoughthere were a number of online resources, our students used to learn vocabulary from textbooks.——
Becausethere were a number of online resources, our students usedn’t to learn vocabulary from textbooks.
Redmond continued to travel and investigate agriculture, thoughhe mostly stayed close to Augusta. ——
Redmond didn’tcontinueto travel and investigate agriculture, becausehe mostly stayed close to Augusta.
Even thoughEmma Joy did very well on her first standardized test, she still has a challenge to face. ——
Because Emma Joy did very well on her first standardized test, she doesn’thave a challenge to face.返回搜狐，查看更多