问如何在SAPI中赋予用户定义的语法比听写语法更优先？

EN

// Create a Grammar for recognizing numeric digits.
Grammar digitsGrammar = CreateDigitsGrammar();
digitsGrammar.Name = "Digits Grammar";
digitsGrammar.Priority = 2;
digitsGrammar.Weight = 0.6f;

// Create a Grammar for recognizing fractions.
Grammar fractionsGrammar = CreateFractionsGrammar();
fractionsGrammar.Name = "Fractions Grammar";
fractionsGrammar.Priority = 1;
fractionsGrammar.Weight = 1f;

// Create an in-process speech recognizer.
SpeechRecognitionEngine recognizer = new SpeechRecognitionEngine();

recognizer.SpeechRecognized +=new EventHandler<SpeechRecognizedEventArgs>(
recognizer_SpeechRecognized);

// Load the digits and fractions Grammar objects.
 recognizer.LoadGrammar(digitsGrammar);
 recognizer.LoadGrammar(fractionsGrammar);

 // Start recognition.
 recognizer.SetInputToDefaultAudioDevice();
 recognizer.RecognizeAsync(RecognizeMode.Multiple);