介于

between / intermediate / to lie between

to introduce / to lie between / between / shell / armor

to go / to take / sentence-final interrogative particle / variant of 於|于[yu2]

(of time or place) in; at; on / (indicating any indirect relation) to; toward; vis-à-vis; with regard to; for / (indicating a source) from; out of / (used in comparison) than / (used in the passive voice) by