‎If A and B are m × n matrices then have the same rank, then the rank of AB must equal the rank of BA.‌‎‌

Let A be an m×n matrix, then ( ). A: AAT =ATA. B: if rank(A) = m, then AT A is invertible. C: if rank(A) = n, then AAT is invertible. D: if rank(A) = n, then AT A is invertible.

以下语句错误的是() A: LECT rank, AVG(salary) FROM people HAVING AVG(salary) > 1000 GROUP BY rank; B: SELECT rank, AVG(salary) FROM people GROUP BY rank HAVING AVG(salary) > 1000 C: SELECT rank, AVG(salary) FROM people HAVING AVG(salary) > 1000 GROUP BY rank; D: SELECT AVG(salary) FROM people GROUP BY rank HAVING AVG(salary) > 1000; E: SELECT rank, AVG(salary) FROM people GROUP BY rank WHERE AVG(salary) > 1000;

在MATLAB中求方阵B的行列式的命令是（ ） A: eig(B) B: B.eval(B) C: C.det(B) D: D.rank(B)

The lowest naval officer rank is ______ , while the lowest army officer rank is ______ .(全部小写)

_____ is the highest rank in grammatical hierarchy and the lowers rank on the textual level. A: Morpheme B: Word C: Phrase D: Sentence

‍‍‍_____ is the highest rank in grammatical hierarchy and the lowers rank on the textual level.‍‍‍‍‍ A: Morpheme B: Word C: Phrase D: Sentence

在ORACLE中，rank()函数和dense_rank()函数的差别是（选一项） A: rank函数和dense_rank函数都没有跳跃 B: rank函数和dense_rank函数都有跳跃 C: rank函数有跳跃 dense_rank函数没有跳跃 D: rank函数没有跳跃 dense_rank函数有跳跃

需要对(A1:A50)单元格区域中的数据进行排名,以下哪个公式运用正确。 A: =Rank(A1,A1:A50) B: =Rank(c2,c2:$c$150) C: =Rank(c2,$c$2:$c$150) D: Rank(c2,$c$2:$c$150)

rank函数最常用的是求某一个数值在某一区域内的排名。rank函数语法形式:rank(number,ref,[order])，ref表示（