Keep An Eye On Him ( watch him carefully1 ... )
keep an eye on sb.意思就是“留意某人的行为”,含有对某人不信任之意。
To "keep an eye on" someone2 is to watch that person3 carefully. Example: "Would4 you keep an eye on my son for me while5 I am gone?" Reply6: "Sure." You take a share7 of responsibility8 for something when you agree9 to keep an eye on it. Example: "I have to run to the bathroom. Can you keep an eye on my suitcase10 while I am away?" Reply: "No problem11." "Keeping an eye on" someone can also mean watching to make sure that person does not make a mistake12. Example: "Be careful what you do today. I'll be keeping an eye on you."