求解线性方程组Ax=b的LU分解法中,A须满足的条件是
A. 对称阵
B. 可逆
C. 任意阵
D. 各阶顺序主子式均不为零
Arrange each of the sequences below in order, from the most abstract word to the most concrete word.(1) farm crops, agriculture, vegetables, potatoes, produce(2) EU, world, Spain, continents, Europe(3) housing complex, building, dining room, structure, apartment(4) Mona Lisa, art, painting, creative activity, portrait(5) automobile, vehicle, Ferrari, transportation, sports car
Rewrite each of the following sentences using clear, familiar words.(1) My employment objective is to attain a position of maximum financial reward.(2) All professors at this school are expected to achieve high standards of excellence in their instructional duties.(3) In the eventuality of fire, it is imperative that all persons evacuate the building without undue delay.(4)All responsibilities connected with the recruiting of new members rest with the club chairman.
Each of the statements below uses one or more of the following stylistic devices: metaphor, simile, parallelism, repetition, alliteration, antithesis. Identify the device (or devices) used in each statement.(1) We must be candid, consistent, and confident.(2) Our opinions have no permanence; like autumn and winter, they gradually pass away.(3) Government of the people, by the people, for the people shall not perish from the earth.(4) The task is heavy, the toil is long, and the trials will be server.(5) From the great grief of one boy’s death came a seed. And from that seed has grown a tree of understanding, a tree that now blossoms with the beauty of friendship and cooperation.(6) We are a people in a quandary about the present. We are a people in search of our future. We are a people in search of a national community.(7) Your success as a family, our success as a society, depends not on what happens at the White House, but on what happens inside your house.