optional fee

基本解释

Optional Admission Fee are mandatory for all Passengers.
自費門票所有團員必須支付。
An optional chargeable (fee-based) function that allows you to create, import, and deploy virtual appliances in your environment.
可選的付費功能，允許在環境中創建、導入和部署虛擬設備。
Airline begins to provide optional service paying fee for the passenger before in 3 years many, included baggage to consign this service among them.
航空公司在三年多以前就開始爲旅客提供可選的付費服務，其中就包括了行李托運這項服務。

Nina also includes a range of existing Nuance text-to-speech voices, and Nuance can develop a custom TTS voice for an optional development fee.
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Instead, Southwest added an optional early bird fee which allows travelers to check in earlier to get a better place in line.
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Part D is an optional insurance program that charges a monthly fee in exchange for prescription drug coverage.
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