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Examine the description of the MARKS table: STD_ID NUMBER(4) STUDENT_NAME VARCHAR2(30) SUBJ1 NUMBER(3) SUBJ2 NUMBER(3) SUBJ3 NUMBER(3) SUBJ1, SUBJ2, and SUBJ3 indicate the marks (grades) obtained by a student in the three subjects. Which two statements are valid? （）
A:SELECT SUM(subj1, subj2, subj3) FROM marks;
B:SELECT SUM(subj1 + subj2 + subj3) FROM marks;
C:SELECT SUM(subj1), SUM(subj2), SUM(subj3) FROM marks;
D:SELECT MAX(subj1, subj2, subj3) FROM marks;
E:SELECT MINIMUM(subj1) FROM marks;
F:SELECT COUNT(std_id) FROM marks WHERE subj1 >= AVG(subj1);

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出自：Oracle认证

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