sets in

The verbs set and sit1 are similar in form and meaning but different in grammatical use. Set is chiefly transitive and takes an object:  Set the dish on the shelf.  Its past tense and past participle are also set:  Yesterday he set three posts for the fence. The judge has set the date for the trial.  Set also has some standard intransitive uses, as “to pass below the horizon” (The sun sets late in the northern latitudes during the summer) and “to become firm, solid, etc.” (This glue sets quickly). The use of set for sit, “to be seated,” is nonstandard:  Pull up a chair and set by me.   Sit is chiefly intransitive and does not take an object:  Let's sit here in the shade.  Its past tense and past participle are sat:  They sat at the table for nearly two hours. Have they sat down yet?  Transitive uses of sit include “to cause to sit” (Pull up a chair and sit yourself down) and “to provide seating for” (The waiter sat us near the window).