In this note, we prove or re-prove several important results regarding one dimensional time fractional ODEs following our previous work [4]. Here we use the definition of Caputo derivative proposed in [8,10] based on a convolution group. In particular, we establish generalized comparison principles consistent with the new definition of Caputo derivatives. In addition, we establish the full asymptotic behaviors of the solutions for D γ c u = Au p . Lastly, we provide a simplified proof for the strict monotonicity and stability in initial values for the time fractional differential equations with weak assumptions.Here θ(t) is the standard Heaviside step function, Γ(·) is the gamma function, and D means the distributional derivative on R. Indeed, g β can be defined for β ∈ R (see [8]) so that {g β : β ∈ R} forms a convolution group. In particular, we haveHere since the support of g βi (i = 1, 2) is bounded from left, the convolution is well-defined. Now we are able to give the generalized definition of fractional derivatives: