Why are drug laws not always a satisfactory deterrent against the use of illicit drugs?

That is because banning drugs doesn't make them less used. Many people start wanting to use them because they are illegal, very often teens and young adults. It becomes sometimes a status symbol to use drugs so people still keep using them even if they are made illegal.

The three steps before modern english were indo-european, germanic, and old english. as peoples moved around the eurasian continent, their languages changed. throughout the ages, the languages became more specialized. as english has many germanic influences, it is easy to see how this was one of the forebears. also, old english was one of the main ancestors of the modern language, spoken in the 5th through about the 13th centuries.