克里斯的答案是正确的，如果你真的需要通过一个可变的DateTime 参考。但是，在很多F＃更地道使用编译器的能力，把尾随退出参数tupled返回值：

Chris's answer is correct if you really need to pass a mutable DateTime by reference. However, it is much more idiomatic in F# to use the compiler's ability to treat trailing out parameters as tupled return values:

let couldParse, parsedDate = System.DateTime.TryParse("11/27/2012")

在这里，首先看重的是布尔返回值，而第二个是分配出去的参数。

Here, the first value is the bool return value, while the second is the assigned out parameter.