In this sentence, "giving himself time to complete the first excuse" is what's called either a "participle phrase" or a "participial phrase". ("Giving" is the present participle of "to give".) And these participial phrases act as adjectives, so "giving himself time to complete..." describes the action of adjusting each item. When these phrases are at the end of a sentence, sometimes there will be a comma, and sometimes not. There's a rule for this. Here are some examples of when a comma is NOT used: - I said hello to the boy playing with the ball. - Joe picked up the coin lying in the street. - We yelled "watch out!" to the man crossing the busy road. In these cases, "playing with the ball", "lying in the street", and "crossing the busy road" both: - Concludes the sentence, and - Describes/modifies the word immediately before it in the sentence ("boy", "coin", "man") If it describes/modifies a word coming earlier in the sentence, you would use a comma. So, to answer your actual question, the reason a comma is used in that sentence is because the participial phrase "giving himself time to ..." doesn't go with the word immediately before it. Without the comma, it implies that there are - somehow - items that give him time to complete something. So these two sentences mean different things, depending on the presence of the comma: - He carefully adjusts each item lying on the table. (the items are lying on the table, and he is carefully adjusting them.) - He carefully adjusts each item, lying on the table. (he is lying on the table, and also he is adjusting some items.)