In css style, the meaning of background-position:-10px 20px is ( ) A: The background<br/>picture is offset by 10px to the left and 20px to the down B: The background<br/>picture is offset by 10px to the left and 20px to the top C: The background<br/>picture is offset by 10px to the right and 20px to the down D: The background<br/>picture is offset by 10px to the right and 20px to the upper

In css, the background picture needs to be located in the lower left corner of the box and should be written as: ( ) A: background-image:left foot B: background-image:left bottom C: background-position:left foot D: background-position:left bottom

word test 2:Match the word in the left column with the proper word or picture in the right column.

Suppose that the demand for picture frames is elastic and the supply of picture frames is inelastic. A tax of $1 per frame levied on picture frames will decrease the effective price received by sellers of picture frames by

若\( A,B,\left( {A + B} \right) \)为同阶可逆方阵，则\( {\left( { { B^{ - 1}} + {A^{ - 1}}} \right)^{ - 1}} = \)（ ） A: \( {B^{ - 1}} + {A^{ - 1}} \) B: \( B + A \) C: \( {\left( {B + A} \right)^{ - 1}} \) D: \( B{\left( {B + A} \right)^{ - 1}}A \)

函数$y = \ln x$，则${\left( {\ln x} \right)^{\left( n \right)}} = {\left( { - 1} \right)^{n - 1}}{{\left( {n - 1} \right)!} \over {{x^n}}}$。（ ）

下列窗体属性中，仅在程序运行时才有效果的是（ ）。 A: Left B: Picture C: BorderStyle D: Caption

‏下列窗体属性中，仅在程序运行时才有效果的是（ ）。‎ A: Left B: Picture C: BorderStyle D: Caption

设\( A,B \)均为\( n \)阶方阵，则必有（ ） A: \( \left| {A + B} \right| = \left| A \right| + \left| B \right| \) B: \( AB = BA \) C: \( \left| {AB} \right| = \left| {BA} \right| \) D: \( {\left( {A + B} \right)^{ - 1}} = {A^{ - 1}} + {B^{ - 1}} \)

函数\(y = {\left( { - 2x + 1} \right)^4}\)的导数为（ ）. A: \( - 8{\left( { - 2x + 1} \right)^3}\) B: \(8{\left( { - 2x + 1} \right)^3}\) C: \(4{\left( { - 2x + 1} \right)^3}\) D: \(- 4{\left( { - 2x + 1} \right)^3}\)