このズボンをあらってもらいたいんですが。

this (something or someone close to the speaker (including the speaker), or ideas expressed by the speaker)

trousers; pants

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to wash; to investigate

yes; yeah; uh huh; negative verb ending used in informal speech (abbr. of negative verb ending "nu"); abbr. of particle "no"; abbr. of particle "ni" (used especially when it precedes the verb "naru")

be; is

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and