OK brains of britain - what's missing (?) from lists :- 1) Y S H S ? N S E 2) D R M ? S L T D 3) W A J M ? A J V H T 4) P T G M k h ? d c m 5) M K D S M ? S L M
4) looks like metric prefixes tera, giga, mega, kilo, hecta (nothing), deci, centi, milli - so the missing thing could be lots of things g for gramme, m for metre etc