Acts 1:3

Shewed himself [π α ρ ε σ τ η σ ε ν]. This verb is rendered in a variety of ways in the New Testament, as give or furnish, present, provide, assist, commend. The original meaning is to place beside, and so commend to the attention. Hence, to set before the mind; present, shew.

Infallible proofs [τ ε κ μ η ρ ι ο ι ς]. The word is akin to tekmar a fixed boundary, goal, end; and hence a fixed or sure sign or token. The Rev. omits infallible, probably, assuming that a proof implies certainty. Being seen [ο π τ α ν ο μ ε ν ο ς]. Only here in New Testament. Rev., appearing.

Forty days [δ ι η μ ε ρ ω ν τ ε σ σ ε ρ α κ ο ν τ α]. Lit., "through forty days." Rev., by the space of. The only passage where the interval between the resurrection and the ascension is given.