You could use either Composite formatting or String interpolation feature.
String.Format makes use of the composite formatting feature:
// Composite formatting:
var string = "The event will take place between {0} and {1}";
var replaced = String.Format(string, "8:30", "9:00");
Or use $ at the beginning of your string and pass the parameters into it very easily:
// String interpolation:
var replaced = $"The event will take place between {"8:30"} and {"9:00"}";
String interpolation provides a more readable and convenient syntax to create formatted strings than a string composite formatting feature.
Visit the following links for more information:
1. String.Format Method
2. $ - string interpolation