当表示事实相符的真实语气时，意为只要，that不可省略；当表示与事实相反的虚拟语气时，意为假如、假设，that可以省略；作为固定搭配时，意为规定。

例句：We shall go provided that the weather is fine.只要天晴, 我们就去。A Web application is provided that allows the operating system service to be easily invoked. 它提供了一个Web应用程序，使操作系统服务易于调用。I will agree to go provided that ( providing that) my expenses are paid.如果帮我支付费用，我就同意去。