提交问题了，然后给回复了，看样子是一共只能用 30G 的硬盘，像我这样一个 30G，一个 8G，那肯定得超了。但是 windows 硬盘又没法减小。那结果就是想免费一个 windows，一个 linux 的愿望没法实现了。
Roxanne from AWS,
So sorry for any confusion caused but please allow me to explain.
30 GB of Amazon Elastic Block Storage in any combination of General Purpose (SSD) or Magnetic, plus 2 million I/Os (with EBS Magnetic) and 1 GB of snapshot storage* is covered under free tier limit if you exceed this you will be charged $0.12 per GB-month of General Purpose SSD (gp2) provisioned storage
For more details, you can review the AWS Free Usage Tier FAQs, along with the Free Tier "Getting Started" guide:
http://aws.amazon.com/free/faqs/http://docs.amazonwebservices.com/gettingstarted/latest/awsgsg-freetier/To help you avoid accidentally exceeding Free Tier limits and incurring charges when you don't mean to, the AWS Billing Console tracks your Free Tier usage through the "Top Free Tier Services by Usage" table, and gives you an estimate of your total usage for the rest of the month. More information on the "Top Free Tier Services by Usage" table here:
http://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/tracking-free-tier-usage.html You can also use Amazon CloudWatch to monitor your AWS service charges and receive Billing Alerts, which can be used to notify you if you accidentally exceed the usage covered by the Free Tier. You can learn how to do that here:
http://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/free-tier-alarms.htmlIf you require any additional information or assistance, please do not hesitate to reach out to me.
Thank you and I hope you have a lovely day ahead of you.
Best regards,
Roxanne P
Amazon Web Services