How many bottles of water should i drink a day?

If the singular term ends in -us, the plural is usually formed by changing the ending to

Employers are required to provide guardrail, safety net, or personal fall protection systems to protect workers from falling off unprotected sides/edges of residential roofs that are feet or more above a lower level.

Which of the following represents the results of a review of well-controlled studies of vitamin c supplementation on the resistance to, and recovery from, colds? there was a reduction in the duration of colds by 50% on the average. there was a slight effect on reducing the duration and severity of colds for people taking vitamin c supplements. there was a significant reduction in the duration of colds in people who consumed at least one gram a day. there was a significant reduction in the number of colds only in people who consumed > three grams per day.