Explain that patents are used to set up trade barriers ().

Explain that patents are used to set up trade barriers ().

A the bill published by the European union in A.2002 requires that low-grade lighters in the European union market must be equipped with safety locks.

B. Foreign enterprises develop D-D on the basis of CD and apply for patent protection.

C wanyan company in China has developed CD equipment.

D-to-D technology patent alliance of D.6C and 3C

Correct answer: ABD