A.T. Robertson Commentary Hebrews 10:1

"For the law having a shadow of the good [things] to come, not the very image of the things, can never with the same sacrifices year by year, which they offer continually, make perfect them that draw nigh." — Hebrews 10:1 (ASV)

Shadow (σκιαν). The contrast here between σκια (shadow, shade caused by interruption of light as by trees, Mr 4:32) and εικων (image or picture) is striking. Christ is the εικων of God (2 Corinthians 4:4; Colossians 1:15). In Col 2:17 Paul draws a distinction between σκια for the Jewish rites and ceremonies and σωμα for the reality in Christ. Children are fond of shadow pictures. The law gives only a dim outline of the good things to come (9:11).

Continually (εις το διηνεκες). See this phrase also in 7:3; 9:12,14. Nowhere else in N.T. From διηνεγκα (διαφερω), to bear through.

They can (δυναντα). This reading leaves ο νομος a nominativus pendens (an anacoluthon). But many MSS. read δυνατα (it--the law--can). For the idea and use of τελειωσα see 9:9.