to gain knowledge or skill by studying, practicing, being taught, or experiencing something —often + about —often + from —often + about —often to + verb
to cause (something) to be in your memory by studying it : memorize
to hear or be told (something) : to find out (something) —+ of
to place (someone or something) down gently in a flat position —often + down
to place (something) into position on or along a surface : to build or set (something) on or in the ground or another surface —often + down —often used figuratively
to hit something (such as a door) with the knuckles of your hand or with a hard object (such as a knocker) in order to get people's attention —usually + on —sometimes used figuratively
to hit (something or someone) in a forceful way
to touch or hit someone or something in a way that is not planned or intended