Rather than trying to teach them English or some other human natural language
Mubin et. al. have suggested that it might be best if robots had their own spoken language (What you say is not what you get, Spoken dialog and human-robot interaction workshop, IEEE, Japan, 2009). My AI Asa H has just such a language as defined in my blogs of 1 Oct. and 5 Nov. 2015 and which
covers Wierzbicka's set of universal semantic primitives (see my blog of 24 May 2013).