When the past tense is used in an independent clause, the dependent clause typically uses tense.
present
future
past
present perfect

When the past tense is used in an independent clause, the dependent clause typically uses past tense. The simple past tense is used to express the idea that an action started and finished at a specific time in the past. It is used for an event that has been completed before the present moment in time.

trade regulation is a field of law, often bracketed with antitrust (as in the phrase “antitrust and trade regulation law”), including government regulation of unfair methods of competition and unfair or deceptive business acts or practices. antitrust law is often considered a subset of trade regulation law. franchise and distribution law, consumer protection law, and advertising law are sometimes considered parts of trade regulation law.

in general the theory of economics says that the more open to trade a country is the better   the result for the same country and the whole economies.

in real life countries impose taxes, quotas, etc which is not so good for the economies.

this kind of commercial war between the usa and china is slowing down the growth of the whole world so we can say that it is a draw back of trade regulations. and the free trade agreements are benefits of trade regulations.

c- companies fail to take environmental protection into account. i think