It's hard to eliminate. The signature strip is made of special material. If you apply liquid medicine or rubber, it is easy to spend, and the word "invalid" appears in Chinese or English in the background. If it's a debit card or a savings account, it doesn't matter whether it's signed or not. You can trade by password. If it is a credit card, the spelling is quite wrong. It is best to call the customer service phone of the credit card to apply for a damaged replacement card and reissue it.