In the Chinese chronicle 'Chunqiu' ('The Spring and Autumn Annals') which describes the history of the Chunqiu Period (771 BC-403 BC), there are 37 solar eclipse observations recorded, starting in 720 BC and ending in 481 BC. Among these, there are ten records which lack either the day of the 60-day cycle or the statement that the eclipse occurred at a 'new Moon' (shuo 朔) or both. A Japanese astronomer, Toshio Watanabe, conjectured that these eclipses may have been observed at sunrise or sunset. In the present paper, we intend to confirm Watanabe's conjecture, and after confirming it, we use these eclipses to accurately determine the range of AT in this period. Our results from five solar eclipses which were accompanied by near-contemporaneous eclipses are: 20,153 < ΔT < 21,094 at around February 2, 720 BC, 18,526 < ΔT<20,686 at around April 15, 676 BC, 19,409 < ΔT < 20,402 at around April 6, 648 BC, if the site is Paros 18,353<ΔT< 19,235 at around April 6, 648 BC, if the site is Thasos 19,172<ΔT<20,910 at around March 6, 598 BC, 16,134<ΔT< 19,101 at around May 31, 558 BC. Finally, we discuss the meaning of the lack of information. Our tentative conclusion is that most (seven out of nine) eclipses without the statement of the first day of the month took place at sunrise or sunset.