When does one use using-directive? how about using-declaration?

I'll be your friend lol.

Evidenceinformation gathered from credible research sources that a speaker support his or her claims.encyclopediaa reference work that offers relatively brief entries providing background information on a wide range of alphabetized topics.peer reviewthe act of subjecting articles submitted to a scholarly journal to critical readings by other experts in a particular field.dictionarya reference work that offers definitions, pronunciation guides, and sometimes etymologies for wordsquotation booka reference work offering famous or notable quotations on a variety of subjectswhat advantages do libraries offer over the internet? libraries allow you access to strong evidence and credible sources that are not available on web sites.describe the advantages and disadvantages of internet research.advantages: allows you convenient access to information on nearly any topic & offers speed-- enabling you to track down a news report or a research finding almost instantly from anywhere in the world. and puts an immense volume of information at our fingertipsdisadvantages: books may not be available online from credible sources, may cost money. cannot assume that information online is credible. anyone can create a website or blog about a topic! what four key characteristics determine a source's credibility? capacityrecency

What did you need with?