cancel的过去式要双写
第三人称单数： cancels
现在分词： cancelling
过去式： cancelled
过去分词： cancelled
No charge will be made if you cancel within 10 days.
如果在10天以内取消，不收费用。
The obvious answer would be to cancel the party.
明摆着的解决方法是取消聚会。
The project has been cancelled because of lack of funds.
这个项目因缺乏资金已经撤销。
