sentences:  Each Sunday or Feast day is assigned one of the eight modes.During the weekday offices, known in Syriac by the name "Shhimo", the 1st and 5th modes are paired together, so are the 2nd and 6th, the 3rd and 7th, and the 4th and 8th.If a particular Sunday makes use of the 1st mode, the following Monday is sung with the 5th mode, Tuesday with the 1st mode, etc., with the pair alternating every day of the week (see the table provided in "Guide to the Eight Modes" in the External Links below).