2. Hong Kong is more crowed than _________ in South America.
A.any city
B.any other city
C. other cities
D. the other cities
第1题:
关系模式CSZ(CITY,ST,ZIP)其属性组上的函数依赖集为F={(CITY,ST)+ZIP, ZIP→CITY},关系模式CSZ的主属性是
A.ZIP
B.CITY,ST,ZIP
C.CITY,ZIP
D.ST,ZIP
第2题:
关系模式CSZ(CITY,ST,ZIP)其属性组上的函数依赖集为F={(CITY,ST)→ZIP,ZIP→CITY},关系模式CSZ的主属性是
A.ZIP
B.CITY,ST,ZIP
C.CITY,ZIP
D.ST,ZIP
第3题:
2、已知柠檬酸(缩写为H3Cit)的pKa1=3.14,pKa2=4.77,pKa3=6.39,若准备配制pH为5.00的缓冲溶液,应选择下列哪对缓冲对。
A.H2Cit-—HCit2-
B.HCit2-—Cit3-
C.H3Cit—H2Cit-
D.H2Cit-— Cit3-
第4题:
关系模式CSZ(CITY,ST,ZIP)其属性组上的函数依赖集为F={(CITY,ST)→ZIP, P→CITY},关系模式CSZ的主属性是
A.ZIP
B.CITY,ST,ZIP
C.CITY,ZIP
D.ST,ZIP
第5题:
If a weather bulletin shows the center of a low pressure system to be 100 miles due east of you, what winds can you expect in the Southern Hemisphere? ______.
A.South-southwesterly
B.North-northwesterly
C.South-southeasterly
D.North-northeasterly
第6题:
已知柠檬酸(缩写为H3Cit)的pKa1=3.14,pKa2=4.77,pKa3=6.39,若准备配制pH为5.00的缓冲溶液,应选择下列哪对缓冲对。
A.H2Cit-—HCit2-
B.HCit2-—Cit3-
C.H3Cit—H2Cit-
D.H2Cit-— Cit3-