The longer parties negotiate, the more willing they are to make concessions. The discussion mentions that roughly ___% of the concessions in a negotiation are made during the last ___% of the negotiation:

80%; 20%

Explanation:

Concessions sometimes called trade off refers to the decision of one party to yield to the demands or positions of the other party in a negotiation either willing or not willingly. Concessions is sometimes based on the length of the negotiation. The longer the negotiations, the more likely a concession is reached by on of the party. Roughly eighty percent of the concessions in a negotiation are made during the last twenty percent of the negotiation:

buildings

explanation:

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.