CLOCKS_PER_SEC代表含义是（）。

不定积分$\int<br/>\tan ^{3}x \sec x\text{d}x=$( ) A: $\frac{1}{3} \sec^3 x+\sec x+C$ B: $\frac{1}{3} \sec^3 x-\sec x+C$ C: $\sec^3 x-\sec x+C$ D: $\sec^3 x+\sec x+C$

Why could pendulum clocks show the hours more exactly than earlier clocks?

The government agency that insures each depositor at a commercial bank, savings and loan association, or mutual savings bank up to a loss of $100,000 per account ($250,000 for individual retirement accounts) is the Securities and Exchange Commission (SEC).

\( \int {\sec x(\sec x - \tan x)dx} = \)( ) A: \( \tan x - \sec x + C \) B: \( \tan x + \sec x + C \) C: \(- \tan x - \sec x + C \) D: \(- \tan x + \sec x + C \)

执行完下列操作后a与b的值分别为（ ） Unsigned char a,b,sec sec=312; a= sec/10; b= sec%10;

设 $y=\tan x^2$，则 $y'=$( ). A: $\sec x^2$ B: $\sec^2 x^2$ C: $2x\sec^2 x$ D: $2x\sec^2 x^2$

雨课堂: \( \int {\sec x(\sec x - \tan x)dx}  = \)(  )

...the clocks may have an implied meaning of __.

下面可以让Div水平居中的css设置是（ ） A: .sec { margin:0 auto; } B: .sec { margin:auto auto; } C: .sec { margin: 0 0; } D: .sec { margin: auto 0;}