郑州大学
设s="HE IS A WORKER",t="WORKER"。则index(s,t,5)的返回值是()。A.4B.5C.6D.9E.10
题目
A.4
B.5
C.6
D.9
E.10
相似问题和答案
第1题：
（33）设关系 R 和S 的元数分别是r 和 s，则集合{t | t = < t r，t s>S }标记的是
A）R ? S
B）R—S
C）R ? S
D）R ? S
第2题：
设关系R与关系S具有相同的目，且相对应的属性的值取自同一个域，则R ∩ S可记作
A．{t | t ∈R ∨ t ∈S}
B．{t | t ∈R ∧ t
S}
C．{t | t ∈ R ∧ t ∈ S}
D．{t | t ∈ R ∨ t
S}
解析：交运算是求两个关系中公共的元组。设有两个结构相同的关系R和S，R和S的交记为R∩S，其结果是一个新关系，有既属于R又属于S的元组组成，可记为R∩s{t │ t∈R∧t∈S}。
第3题：
设关系R与关系S具有相同的目，且相对应的属性的值取自同一个域，则R ? S可记作
A．{t | t ?R ú t ?S}
B．{t | t ?R ù t ?S}
C．{t | t ?R ù t ?S}
D．{t | t ?R ú t ?S}
第4题：
设关系R和关系S的元素分别是4和5，关系T是R与S的笛卡尔积，即：T＝ R×S，则关系T的元数是( )。
A．9
B．16
C．20
D．25
第5题：
A flesh ;
B fresh ;
C flash
第6题：
（ 34 ）设关系 R 与关系 S 具有相同的属性个数，且对应属性的值取自同一个域，则 R ? S 可记作
A ） {t | t ∈ R ∨ t ∈ S}
B ） {t | t ∈ R ∧ t ? S}
C ） {t | t ∈ R ∧ t ∈ S}
D ） {t | t ∈ R ∨ t ? S}
第7题：
Henry's job was to examine cars which crossed the frontier to make sure that they were not smuggling anything into the country. Every morning，except at weekends，he (11) see a factory worker coming up the hill towards the frontier， (12) a bicycle with a big load of old straw on it. When the bicycle arrived the frontier，Henry used to stop the man and order him to take the straw off. Then he would examine the straw very carefully to see (13) he could find anything，after which he would look in all the man's pockets before he let him tie the straw up again. The man would then put it on his bicycle and go off down the hill with it. Although Henry was always (14) to find gold or jewelry or other valuable things hidden in the straw，he never found (15) ，even though he examined it very carefully. He was sure that the man was smuggling something，but he was not (16) 鱼to imagine what it could be.
Then one evening，after he had looked through the straw and emptied the factory worker's pockets (17) usual，he said to him，“Listen，I know that you are smuggling things (18) this frontier. Won't you tell me what it is that you're bringing into the country so successfully? I'm an old man，and today's my last day on the job. Tomorrow I'm going to (19) . I promise that I shall not tell anyone if you tell me what you've been smuggling. ”The factory worker did not say anything for (20) . Then he smiled，turned to Henry and said quietly：“Bicycles. ”
A. should
B. might
C. would
D. must
[解析] 情态动词would用以表达习惯性“总是，总会”。
第8题：
●设关系R是4元关系，关系S是一个5元关系，关系T是R与S的笛卡儿积，即T=R×S，则关系T是 (22) 元关系。
(22) A．14
B．9
C．24
D．42
【解析】根据笛卡儿积的定义：有n元关系R及m元关系S，它们分别有p、q个元组，则关系R与S经笛卡儿积记为R×S，该关系是一个n+m元关系，元组个数是p×q，由R与S的有序组组合而成。
第9题：
He doesn’t believe the worker can ____________ to assemble the motorcycle all by himself.
A、succeed
B、pursue
C、manage
D、handle
第10题：
A.4
B.5
C.6
D.9
E.10