We have every reason to cancel the contract because you've failed to fulfil your part of it.
我们完全有理由取消合同,因为你们没有完成应遵守的合同内容,履行合同。
This ran on an 'operating system' called DOS, produced by a then small company named Microsoft.
这种电脑采用了一种被称为磁盘操作系统(DOS)的工作程序,而这种程序是由当时规模不大的微软公司生产的。