Legal analysis: I have to sign it. When entrusting others to exercise their legitimate rights and interests on their behalf, the client shall show the legal documents of the client when exercising his power. The trustor shall not abandon the entrusted matters for any reason. The power of attorney shall specify the agent's name, agency matters, authority and time limit, and shall be signed or sealed by the principal.

Legal basis: Article 65 of the Civil Procedure Law of People's Republic of China (PRC), the parties shall provide evidence of their claims in time. The people's court shall, according to the litigant's claim and the trial of the case, determine the evidence that the litigant should provide and its time limit. If it is really difficult for the parties to provide evidence within the time limit, they may apply to the people's court for an extension of the time limit, and the people's court shall extend the time limit appropriately according to the application of the parties. If a party fails to provide evidence within the time limit, the people's court shall order it to explain the reasons; If the people's court refuses to explain the reasons or the reasons cannot be established, it may reject the evidence according to different circumstances, or accept the evidence but admonish it and impose a fine.