When applying for a visa extension state simply and clearly the reasons why you need an extension.

申请签证续签时，简单明了地陈述你需要延期的理由。

《柯林斯英汉双解大词典》

They are processing my visa extension.

他们正在处理我的签证延期。

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Your request for a visa extension has been turned down because you do not have sufficient funds.

因为您的资金不足，你想延长签证的要求已被驳回。

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The deals with Mastercard and Visa represent an extension of a partnership Foursquare has had since 2011 with American Express.

FORBES: Foursquare Inches Toward Profitability With Visa, MasterCard Deals

By extension, then, the Visa and MasterCard rules have applied to both Amex and Discover.

FORBES: Credit Card Changes Looming: Merchants Will Be Allowed to Add Surcharges