“…Clearly, the first eigenvalue l 0 has multiplicity one and constant eigenfunction. In recent years, there are some interesting results concerning eigenvalue estimates of the drifting Laplacian and the bi-drifting Laplacian-see, e.g., [9,11,12,15,18,21,22,23,30]. When ðM; h ; iÞ is immersed into the Euclidean N-space ðR N ; canÞ with the canonical metric can, one can define the weighted mean curvature vector as ? , where H is the mean curvature vector of M in R N , ð'f Þ ?…”