下列对CSS选择器表述错误的是（） A: .intro---选择class="intro"的所有元素。 B: C: firstname---选择id="firstname"的元素。 D: div>p---选择所有元素和所有元素 E: p---选择所有元素

下面代码的输出是什么?（） functionPerson(firstName,lastName){ this.firstName=firstName; this.lastName=lastName; } constlydia=newPerson("Lydia","Hallie"); constsarah=Person("Sarah","Smith"); console.log(lydia); console.log(sarah); A: Person{firstName:"Lydia",lastName:"Hallie"}andundefined B: Person{firstName:"Lydia",lastName:"Hallie"}andPerson{firstName:"Sarah",lastName:"Smith"} C: Person{firstName:"Lydia",lastName:"Hallie"}and{} D: Person{firstName:"Lydia",lastName:"Hallie"}andReferenceError

从"actor"表中选取"FirstName"列的SQL语句是()。 A: select actor.FirstName B: select FirstName from actor C: extract FirstName from actor D: update FirstName from actor

#firstname{css属性对列表}，样式应用于 id="firstname" 的所有元素

通过 SQL，在 "Actor" 表中删除 "FirstName" 等于 "Fred" 的记录的描述正确的是（）。 A: DELETE FirstName='Fred' FROM Actor B: DELETE ROW FirstName='Fred' FROM Actor C: DELETE Actor WHERE FirstName = 'Fred' D: DELETE FROM Actor WHERE FirstName = 'Fred'

通过 SQL，您如何根据 "FirstName" 列降序地从 "Persons" 表返回所有记录？ A: SELECT * FROM Persons SORT 'FirstName' DESC B: SELECT * FROM Persons ORDER BY FirstName DESC C: SELECT * FROM Persons ORDER FirstName DESC D: SELECT * FROM Persons SORT BY 'FirstName' DESC

通过 SQL，您如何从 "Persons" 表中选取 "FirstName" 列的值以 "a" 开头的所有记录？ A: SELECT * FROM Persons WHERE FirstName LIKE 'a%' B: SELECT * FROM Persons WHERE FirstName='a' C: SELECT * FROM Persons WHERE FirstName LIKE '%a' D: SELECT * FROM Persons WHERE FirstName='%a%'

通过 SQL，您如何在 "Persons" 表中删除 "FirstName" 等于 "Fred" 的纪录？ A: DELETE FROM Persons WHERE FirstName = 'Fred' B: DELETE FirstName='Fred' FROM Persons C: DELETE ROW FirstName='Fred' FROM Persons

通过 SQL，您如何从 "Persons" 表中选取 "FirstName" 列？ A: SELECT Persons.FirstName B: SELECT FirstName FROM Persons C: EXTRACT FirstName FROM Persons

通过 SQL，根据 "FirstName" 列降序地从 "Actor" 表返回所有记录的正确表述是 A: SELECT * FROM Actor SORT BY 'FirstName' DESC B: SELECT * FROM Actor ORDER FirstName DESC C: SELECT * FROM Actor SORT 'FirstName' DESC D: SELECT * FROM Actor ORDER BY FirstName DESC