fix: 查看原卷判断题答案展示问题

src/features/examwork/StudentExamDetail/PreviewPaperDialog.vue

@@ -468,7 +468,7 @@ export default {
       } else {
         let ansCont = "";
         if (structType === STRUCT_TYPES.BOOLEAN_CHOICE) {
-          ansCont = answer ? "对" : "错";
+          ansCont = answer === "" ? "" : answer ? "对" : "错";
         } else {
           ansCont = answer.map((item) => OPTION_NAME[item - 1]).join("");
         }