The first in the series is here.ב
Bet has an enormity of meanings. BDB lists all of these: in, among, within, into, on, at, by, against, down to, upon, with, and others. How can one approach such flexibility in a single initial letter!
The grammar books all introduce בּ simply, with a single word, usually in a house בבית or in the house בָבית. I admit it has taken me three years to dare to read the pages on in BDB. It was a cure for insomnia a few nights ago. Fascinating examples to be drawn out but let's see a few of the uses of ב in Ruth.
The traditional meaning 'in' occurs frequently, especially in the phrase בִּשְׂדֵי מוֹאָב in the fields of Moab. A rendering of 'against' is required for Naomi's statement: כִּי-יָצְאָה בִי יַד-יְהוָה for the hand of יְהוָה has come out against me. 'To' is needed for the very next verse: וְרוּת דָּבְקָה בָּהּ but Ruth stayed close to her.
Here is one related to field where rather than 'in', 'on' is intended: עֵינַיִךְ בַּשָּׂדֶה אֲשֶׁר-יִקְצֹרוּן your eyes on the field where they reap. And here a spot where it is demanded by the verb but would not be rendered in English: וְלֹא תִגְעֲרוּ-בָהּ and do not rebuke her. Altogether, a 'sounds like' or concordant translation is clearly impossible for this preposition.
BDB speaks of three broad classifications: beth vasculi, beth coniunctionis et viciniae, and beth auxilii but the 22 subsequent subclassifications in four major groups (I. In, II Denoting proximity, III With, IV with certain classes of verbs) do not use these divisions.
appearing as 'as'
וָאֵרָא אֶל־אַבְרָהָם אֶל־יִצְחָק וְאֶֽל־יַעֲקֹב בְּאֵל שַׁדָּי וּשְׁמִי יְהוָה לֹא נֹודַעְתִּי לָהֶםand I appeared to Abraham, to Isaac, and to Jacob as El Shaddai, but the name יְהוָה I was not known to them
Examples are everywhere - so no more multiplication. Bet keeps its place in the letters that act grammatically.