1999 one's deceased father grind mathematics 2 multiple-choice questions 4 involves the definition of limit. . I hope the great god can explain it to me. . . Especially ε 1. What do you mean? thank you Because 2ε has been given in the original question, it should be distinguished from it when proving sufficiency, so it is set to ε 1, which is ε in the limit definition. You should not limit whether there is 1 in the symbol. You should change 2ε in the original title to 2t, and then change ε 1 in the definition to ε to see if you can understand it.