\" 转义字符， \a系统警报，逐字字符串(verbatim string)

 string str="The key factors are \"focus\" and \"perseverance\"";

 string str = "All finished.\n\n\n\n \a";

string str = @"This world is fair
and everything can exist must be reasonable
Everything depend on myself.Devote myself into .net and coding.Spare no efforts on work.
Stay focused and keep shipping.";