An adverbial clause of concession denotes the presence of some obstacle which nevertheless does not hinder the action expressed in the principal clause: there is a contrast between the content of the principal clause and that of the subordinate one.
Adverbial clauses of concession are introduced by the following conjunctions and connectives: though, although, as, no matter how, however, whereas, while, whilst, whoever, whatever, whichever, no matter what, for all that, despite that, in spite of the fact, despite the fact, even if, even though, even when, except that, notwithstanding that, not that.
However, contrastive meaning is not characteristic of all types of concessive clauses. There are three types of concessive clauses, which differ in the relation they bear to the principal clause and in the way they are connected.
1. Clauses of admitted concession (придаточные уступительные со значением допущения).
Though there might be many obstacles to overcome, he faithfully believed in future.
Though all efforts fail, we shall never surrender.
Concessive clauses introduced by compound pronouns and adverbs in -ever are never adversative to the main clause in their content, as they suggest a choice from among a number of possibilities.
Whoever he may be, he seems to be an honest man at least.
Wherever you live, you can keep a cat.
Clauses of admitted concession may have inverted word order; inversion is possible both with the conjunctions though and as, which in this case occur in non-initial position (after the predicative), and with conjunctive words.
Josephine could always eat, however excited she was (though she was excited).
Dark as it was getting, I could still see these changes (though it was getting dark).
Miraculous though it seemed to be, there was no miracle in their survival (though it seemed to be miraculous).
2. Clauses of open concession (придаточные уступительные со значением гипотетического допущения). Clauses of this type express an unreal condition, despite which the action in the principal clause is carried out. The predicate in the subordinate clause may be in the indicative or in the subjunctive mood (in the latter case the subjunctive forms with may and might are generally used).
Whatever may be the shortcomings and defects of the present treatment, it is vain to attempt to extenuate or excuse them in a short preface.
However much advice you give him, he does exactly what he wants.
3. Clauses of disjunctive or alternative concession (придаточные уступительные со значением альтернативы). These clauses admit two possible alternatives, both of which may be unreal, or may refer to the future. As can be seen from the examples given below, the contrast between the principal and the subordinate clause or clauses is weaker, as there are two alternatives, neither of which can be considered as an acceptable condition.
“Coward!” he repeated. “Coward, am I? Then I'll be a coward, and you shall kiss me whether you will or not!”
The conjunctions although, though, while, and whilst are sometimes used in non-finite concessive clauses. For example, instead of saying Although he liked cats, he never let them come into his house, we can say Although liking cats, he never let them come into his house.
While conceding the importance of freedom of speech, I believe it must be exercised with sensitivity and responsibility.
Despite and in spite of can also be used at the beginning of non-finite concessive clauses.
Despite working hard, I failed my examsmeans Although I worked hard, I failed my exams.
Although, though, while, and whilst are also used in front of noun groups, adjective groups and predicatives.
It was an unequal marriage, although a stable and long-lasting one.
Though not very attractive physically, she possessed a sense of humour.
They had followed her suggestion, though without much enthusiasm.