The parser recognized commands as you typed them in English imperative:

   "drop handkerchief" would make you to drop a handkerchief, if you had one.

For simplicity do not include articles (a,an,the) in the commands:

   "get bottle from bag" would get a bottle from the bag.

You can address multiple instances of a similar named object by count number:

   "drop bottle 3" would drop third bottle in your inventory (try "i" command).

Prepositions are usually handled with no problems. Some commands though do not
understand all possible prepositions, nor all possible word orders. Atleast
following commands require standard form:

   look
   look at <what>
   drop <what>
   get <what>
   get <what> from <what>
   give <what> to <whom>
   put <what> in <what>

