well... it depends. For example, if you say: "How many times have you got knocked by life?" you are asking how many times the life have given a knocked in someone (maybe not from a person). but if you say: "How many times have you got knocked in life?" you are asking how many times anybody in life has received a knocked from someone (from a person). is it clear for your?

Hi Heshel. It’s impossible to tell you which is correct when you don’t specify what it is you want to express. This might help you: Knock down=to cause to fall to the ground: “He hit him on the chin and knocked him down.” “The storm knocked down several big trees.” Knock out someone= to hit someone so that the person becomes unconscious, or to cause someone to go to sleep: “His fall from the ladder knocked him out.” “Those sleeping pills knocked me out.”

1. How many times have you been knocked down in life? 2. How many times have you been knocked out in life? 1. How many times have you been knocked down by hardships? 2. How many times have you been knocked out by hardships? "in life" is more often used than "by life". Source: asking Google :) "knocked down in life" — 335,000 results "knocked down by life" — 22,200 results "knocked out in life" — 1,510,000 results "knocked out by life" — 49,200 results ... and I think it is because "in lifetime", so it is period of time "by" is more about of usage for some tool or method ~~~ off-topic: “It's not how many times you get knocked down that count, it's how many times you get back up. ” George A. Custer // U.S. Military You may be knocked down, But not out forever, Lose our way, Get back up again, So get up, get up, You gonna shine again! Toby Mac, song "Get Back Up" ;)