What goes in the empty boxes

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.

Mario was conducting research regarding the treatment of aids victims using stem cells. he found a source that was written recently and the author was known. unfortunately, he could not determine if it had been peer reviewed.

Which diseases are drug abusers particularly susceptible to