设方阵\( A \)和\( B \) 等价，\( A \) 的所有\( k \) 阶子式全为零，则( ) A: \( r\left( B \right) < k \) B: \( r\left( B \right) = k \) C: \( r\left( B \right) \ge k \) D: \( r\left( B \right) \le k \)

1.设${{J}_{k}}=\int_{{}}^{{}}{\frac{dx}{{{\left[ {{(x+a)}^{2}}+{{b}^{2}} \right]}^{k}}}}\quad (b\ne 0)$，则${{J}_{k}}$满足( )。 A: ${{J}_{k+1}}=\frac{1}{2k{{b}^{2}}}\left[ (x+a){{\left( {{(x+a)}^{2}}+{{b}^{2}} \right)}^{-k}}-(2k-1){{J}_{k}} \right],\quad (k\ge 2)$ B: ${{J}_{k+1}}=\frac{1}{2k{{b}^{2}}}\left[ (x+a){{\left( {{(x+a)}^{2}}+{{b}^{2}} \right)}^{-k}}+(2k-1){{J}_{k}} \right],\quad (k\ge 2)$ C: ${{J}_{k+1}}=\frac{1}{2{{b}^{2}}}\left[ (x+a){{\left( {{(x+a)}^{2}}+{{b}^{2}} \right)}^{-k}}+(2k+1){{J}_{k}} \right],\quad (k\ge 2)$ D: ${{J}_{k+1}}=\frac{1}{2{{b}^{2}}}\left[ (x+a){{\left( {{(x+a)}^{2}}+{{b}^{2}} \right)}^{-k}}+(2k-1){{J}_{k}} \right],\quad (k\ge 2)$

计算向量场$A = \left( {{x^2} - y} \right)i + 4zj + {x^2}k$的旋度。 A: $4i+ 2xj - k$ B: $ - 4i - 2xj - k$ C: $ 4i +2xj + k$ D: $ - 4i - 2xj + k$

在网页中插入两个id名分别为left和right的<;div>;标签，（）两个元素都右浮动。 A: B: left, C: right{float:left;} D: E: left, F: right{float:right;} G: H: left{float:left;} I: right{float:right;} J: K: left{width:100px;float:left;} L: right{margin-left:100px;}

Word2010的表格计算中有三个函数参数，分别是（）。 A: ABOV B: LEF C: RIGHT D: U E: DOW F: LEFT G: ABOV H: BOTTO I: RIGHT J: DOW K: LEF L: RIGHT

如果\( k = \lim \limits_{x \to \infty } { { f\left( x \right)} \over x},b =\lim \limits_{x \to \infty } \left( {f\left( x \right) - kx} \right) \)，则称\( y = kx +b\)为曲线\( y = f(x) \) 的一条______ 。

Before administering a medication, the nurse must verify the rights of medication administration, which include: A: right patient, right bed, right drug, right route, right dose, and right time. B: right drug, right dose, right route, right time, right physician, and right documentation. C: right patient, right drug, right route, right time, right documentation, and right equipment. D: right patient, right drug, right dose, right concentration, right route, right time, and expiration date.

     说明下列信号是周期信号还是非周期信号,如果是周期信号,试确定其周期。[br][/br]x(k)= e ^{ j ^{\left(\frac{k}{4}- x \right)}}

第2类拉格朗日方程表达式为____ 。 A: $\frac{{\rm{d}}}{{{\rm{d}}t}}\left( {\frac{{\partial T}}{{\partial {{\dot q}_k}}}} \right) - \frac{{\partial T}}{{\partial {q_k}}} = 0$ B: $\frac{{\rm{d}}}{{{\rm{d}}t}}\left( {\frac{{\partial T}}{{\partial {{\dot q}_k}}}} \right) - \frac{{\partial T}}{{\partial {q_k}}} = {Q_k}$ C: $\frac{{\rm{d}}}{{{\rm{d}}t}}\left( {\frac{{\partial T}}{{\partial {{\dot q}_k}}}} \right) + \frac{{\partial T}}{{\partial {q_k}}} = {Q_k}$ D: 以上都不对

____________is defined by many marketers as “putting the right product in the right place, at the right price and right time.”