21.在Visual FoxPro中，可以包含數(shù)據(jù)環(huán)境的對象是(       )

A.報(bào)表                                                        B.數(shù)據(jù)表

C.菜單                                                        D.數(shù)據(jù)庫

22.在Visual FoxPro數(shù)據(jù)庫中，實(shí)現(xiàn)數(shù)據(jù)安全性、完整性、可靠性校驗(yàn)主要依靠(       )

A.程序語句                                                 B.數(shù)據(jù)字典

C.操作員                                                    D.界面控制

23.需要用熱鍵F操作下拉菜單某選項(xiàng)，創(chuàng)建菜單該選項(xiàng)時(shí)應(yīng)當(dāng)在相應(yīng)的“菜單名稱”項(xiàng)中輸入(       )

A.(\F)                                                         B.(\<F)

C.(<F)                                                        D.(\F)

24.數(shù)據(jù)庫表中字符型字段的默認(rèn)匹配類是(       )

A.組合框                                                    B.文本框

C.列表框                                                    D.編輯框

25.在面向?qū)ο蠓椒ㄖ�，一組對象的屬性和行為特征的抽象描述稱為(       )

A.操作                                                        B.事件

C.方法                                                        D.類