设A、B均为n阶方阵,则下面结论正确的是()。
A.若A或B可逆,则AB必可逆
B.若A或B不可逆,则AB必不可逆
C.若A、B均可逆,则A+B必可逆
D.若A、B均不可逆,若A+B必不可逆
Listen to the passage and complete the following missing information.(Eunit 6 ) In the humanities, authors write to inform you in many ways. These methods can be (1) _________________ into three types of informational writing: factual, descriptive, and process.Factual writing provides (2) ______________ information on an author, composer, or artist or on a type of music, art, or literature. Examples of factual writing include notes on a book jacket or (3) _____________ cover and longer pieces, such as an article describing a style of music which you might read in a music (4) ________________ course. This kind of writing provides a (5) ______________ for your study of the humanities.As its name (6) _________________, descriptive writing simply describes, or provides an (7) _____________ of a piece of music, art, or literature. For example, descriptive writing might list the colors an artist used in a painting or the (8) ______________ a composer included in a musical composition, so as to make pictures or sounds in the reader’s mind by calling up specific details of the work. Descriptive writing in the humanities, particularly in literature, is often (9) ___________ with critical writing.Process writing explains a series of actions that bring about a result. It tells the reader how to do something, for example, explaining the technique used to shoot a film. This kind of writing is often found in art, where understanding how an art has created a certain effect is important. Authors may (10) ________________ use more than one type of technique in a given piece ofinformational writing.