diff --git a/frontend/app/learn/page.tsx b/frontend/app/learn/page.tsx
index 09a0625..39f7d80 100644
--- a/frontend/app/learn/page.tsx
+++ b/frontend/app/learn/page.tsx
@@ -9,13 +9,13 @@ import LearningComplete from '@/components/LearningComplete'
 import ReviewTypeIndicator from '@/components/review/ReviewTypeIndicator'
 import MasteryIndicator from '@/components/review/MasteryIndicator'
 import { flashcardsService, type Flashcard } from '@/lib/services/flashcards'
-import { calculateCurrentMastery, getReviewTypesByDifficulty, isA1Learner } from '@/lib/utils/masteryCalculator'
+import { calculateCurrentMastery, getReviewTypesByDifficulty } from '@/lib/utils/masteryCalculator'
 
 // 擴展的Flashcard接口，包含智能複習需要的欄位
-interface ExtendedFlashcard extends Flashcard {
+interface ExtendedFlashcard extends Omit<Flashcard, 'nextReviewDate'> {
   userLevel?: number;        // 學習者程度 (1-100)
   wordLevel?: number;        // 詞彙難度 (1-100)
-  nextReviewDate?: string;   // 下次復習日期
+  nextReviewDate?: string;   // 下次復習日期 (可選)
   currentInterval?: number;  // 當前間隔天數
   isOverdue?: boolean;       // 是否逾期
   overdueDays?: number;      // 逾期天數