keep something/ someone away means to avoid doing something/ someone (e.g. We can’t keep the kids away from the electronic game.)
keep away from means don't go near (e.g. You should keep away from hot foods. Keep away from the edge of the pool. You might fall in.)

keep something from someone means not tell or control yourself, refrain (e.g. We kept our relationship from our friends for a year.)
keep from something means to prevent from doing something (e.g. Ann could hardly keep from laughing.)

keep on (doing something) means do it continuously or repeatedly (e.g. The rain kept on all weekend. Keep on stirring until the meat is properly cooked.)

keep somebody/ something out means not allow someone to enter (e.g. Try to keep the wet dog out of the living room.)

keep out of something means to not become involved with something (e.g. Keep the skin out of the sun.)

keep up (with somebody) means continue at the same speed or level, persist (e.g. You're walking too fast and it’s really hard to keep up (with you), You're doing well. Keep it up!)

keep up with means move at the same rate that is happening or changing very fast (e.g. The actual value of wages is failing to keep up with inflation.)

knock down means hit and injury somebody, or extremely cheap (e.g. The car dealer is selling cars for ridiculous knock down prices.)
knock somebody/ something (blow, cut) down means to fall to the ground by hitting, or demolish means (e.g. You need to cut (knock) down the tree in your garden as soon as possible. The lorry knocked the passenger car down and escaped immediately.)

knock out means to hit the person and becomes unconscious, or sell or distribute (e.g. The champion was knocked out by the challenger’s lucky punch. New sales man knocks over ten cars out a day.)