A．ll flights _________ because of the snowstorm, many passengers could do nothing but take the train.

A．) had been canceled               B) have been canceled

C．) were canceled                   D) having been canceled

 

[单选题]Mary ______ in bed all day because she had a fever.A． layB． has laidC． has lainD． laid

[问答题]We all like her because she is very helpful.

[单选题]It is because he is kind and modest ________ he wins the respect of all pre

[判断题]All Risks are the most comprehensive type of cover because it covers allkin

[判断题]All Risks are the most comprehensive type of cover because it covers allkin

[单选题]Because his workplace was so busy and noisy，he longed most of all for______

[单选题]It is difficultto list all of John's [attributes] because he has so many di

[单选题]设关系R(SNO，SNAME，DNO，MAG)，主键为SNO。其中，SNO为学号，SNAME为学生姓名，DNO为系号，MAG为系主任，则关系R属于A．1NFB．2NFC．3NFD．不属于任何范式

[单选题]设关系R(SNO，SNAME，DNO，MAG)，主键为SNO。其中SNO为学生号，SNAME为学生姓名，DNO为系号，MAG为系主任。则关系R属于A．1NFB．2NFC．3NFD．不属于任何范式

[单选题]16) 设有关系 SC(SNO,CNO,GRADE), 其中 SNO 、 CNO 分别表示学号和课程号 ( 两者均为字符型 ) ，GRADE 表示成绩 ( 数值型 ) 。若要把学号为 “ S101 ” 的同学，选修课程号为 “ C11 ” , 成绩为 98 分的记录插入到SC 中 ，正确的语句是A．)INSERT INTO SC(SNO,CNO,GRADE) VALUES ( 'S101' , 'C11' , '98' )B．)INSERT INTO SC(SNO,CNO,GRADE