1. The distinction between a language and a dialect is a ---- difficult one.

2. Japan is often ---- as an example of a country that has managed to keep its national defence orientated industries
entirely separate from foreign-owned companies.

3. The general feeling in the court was that several of the witnesses were ---- information that could have a direct
bearing upon the case.

4. Acid rain only became a ---- environmental issue in the 1980s following groundbreaking studies in the 1970s.

5. Using the dam to generate power would not ---- the treaty with the neighboring country, but diverting water out of the river would.