下面是给出这几个结构体的构造函数、析构函数和默认构造函数的示例：
struct st_answer_trueOrfalse {bool banswer;bool banswer_standard;bool bret;st_answer_trueOrfalse() : banswer(false), banswer_standard(false), bret(false) {}};struct st_answer_choose {int banswer;int banswer_standard;bool bret;st_answer_choose() : banswer(0), banswer_standard(0), bret(false) {}};struct st_answer_choose_multiple {QList<QString> banswer;QList<QString> banswer_standard;bool bret;st_answer_choose_multiple() : bret(false) {}};union st_subject_Type {st_answer_trueOrfalse trueOrfalse;st_answer_choose choose;st_answer_choose_multiple choose_multiple;// 析构函数（可选）~st_subject_Type() {}};struct st_subject {int subject_number;int subject_itype;QString subject_name;st_subject_Type subject_Type;QImage image;int score;// 默认构造函数st_subject() : subject_number(0), subject_itype(0), score(0) {}// 构造函数st_subject(int number, int type, const QString& name, const QImage& img, int s): subject_number(number), subject_itype(type),subject_name(name), image(img), score(s) {}// 析构函数（可选）~st_subject() {}};
以上是基于 C++ 的示例代码，使用了成员初始化列表语法来初始化各个成员变量。根据实际需要可以对默认构造函数和析构函数进行扩展，以实现更复杂的逻辑。
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