It (aims to) establish a minimum list of standards that (ought to) (include) in all codes of conduct (covering) labor practices.

单项选择题China has established three (nature reserves) to protect (the rare species), covering (a total of) more than 600,000 sq km, an area (40 times of the size) of Beijing.

单项选择题It is perhaps not an exaggeration (to say) that we shall soon (be trusting) our health, wealth, and happiness to elements with (whom) very name the general public (are) unfamiliar.