We can infer from Dr. Myers and Dr. Worm’s paper that ________.
[A] the stock of large predators in some old fisheries has reduced by 90%
[B] there are only half as many fisheries as there were 15 years ago
[C] the catch sizes in new fisheries are only 20% of the original amount
[D] the number of larger predators dropped faster in new fisheries than in the old
第1题:
Our tradition ______ be different _____ yours.
A、can;with
B、must;with
C、need;as
D、may;from
第2题:
A. wouldn’t go out
B. can’t go out
C. won’t go out (will not)
第3题:
第4题:
A. must have
B. can’t have
C. should have
D. needn’t have
答案:D
解析:根据题意选D。
本句意思:我们应该已经预订过了。看,这家餐厅几乎空无一人。
must have意思为:“必须已经”;can’t have“不能”;should have意思为:“应该已经”;needn’t have意思为:“不必”,
第5题:
27.If we travel by car ,we_________.
A. can't travel fifty or one hundred miles a day
B. can-t stop at a hotel to spend the night
C. can make our own timetable '
D. can travel to a very far place in several minutes
第6题:
现有学生社团管理数据库,其中包括基本表如下: 学生(学号,姓名,所在系); 社团(社团编号,名称,成立时间,社长),其中社长由该社团中学生担任; 参加(学号,社团编号,参加时间,职务),其中若不担任任何社团职务,属性“职务”为空; 若要查询参加了学生“李明”所参加的所有社团的学生学号、姓名和所在系,正确的SQL语句是()。
A.SELECT * FROM 学生, 参加 WHERE 参加.学号=学生.学号 AND 姓名='李明;#B.SELECT * FROM 学生 S1 WHERE 学号 IN (SELECT 学号 FROM 参加 WHERE 社团编号 IN (SELECT 社团编号 FROM 参加, 学生 WHERE 参加.学号=学生.学号 AND 姓名='李明'));#C.SELECT * FROM 学生 S1 WHERE NOT EXISTS (SELECT * FROM 参加 P1, 学生 S2 WHERE P1.学号=S2.学号 AND S2.姓名='李明' AND NOT EXISTS (SELECT * FROM 参加 P2 WHERE P2.学号=S1.学号 AND P2.社团编号=P1.社团编号));#D.SELECT * FROM 学生 S1 WHERE EXISTS (SELECT * FROM 参加 P1, 学生 S2 WHE