Zhan Kuan GUO,Jiong SUN
							
							
							
								In the paper, we considered a class of ordinary differential expressions as following:=0(-1)kDkeanxDk and =0(-1)kakDkenxDk, proved that their  indexes are {n, n + 2,..., 2n- l} or {n, n + 2,..., 2n-2} or a subset of them, and gave some examples of positive coefficient ordinary differential operators with middle  deficiency indexes. These examples show that positive coefficient ordinary differential operators needn't to be all limit-point, this is, we give a negative answer to Everitt's conjecture in another way.