Instructions: select all the correct answers. in what three ways did the chinese develop the perpetual calendar wan-nien-li? 1.they observed the sun's longitude and the moon's phases. 2.they used measurements from a sundial and a water clock. 3.they determined the dates of the two solstices in a year. 4.they mapped the constellations in the night sky. 5.they surveyed citizens about how many days there should be in a year.