【单选题】
Professor White is out of office right now. Can you leave a_________ or call later?
①
message
②
information
③
idea
④
advice
【单选题】
设整型变量a=2，则执行下列语句后，浮点型变量b的值不为0.5的是（ ）。
①
b=1.0/a
②
b=(float)(1/a)
③
b=1/(float)a
④
b=1/(a*1.0)
【单选题】
---Why didn’t John call me ? ---Oh, his cell-phone ran out of power, otherwise he______ you.
①
had called
②
would have called
③
called
④
would call
【单选题】
__Why didn’t John call me ?
__Oh, his cell-phone ran out of power, otherwise he______ you.
①
had called
②
would have called
③
called
④
would call
【单选题】
下列二元函数中， 可以作为连续型随机变量的联合概率密度
①
<img class=jc-formula data-tex=f(x,y)=\begin{ cases } cosx,\quad -\frac { \pi }{ 2 } \le x\le \frac { \pi }{ 2 } ,\quad 0\le y\le 1 \\ 0, \end{ cases } src=https://huaweicloudobs.ahjxjy.cn/422A8E9517DD75A11B7D84583C5C1839.png style=vertical-align: middle;/>
②
<img class=jc-formula data-tex=g(x,y)=\begin{ cases } cosx,\quad -\frac { \pi }{ 2 } \le x\le \frac { \pi }{ 2 } ,\quad 0\le y\le \frac { 1 }{ 2 } \\ 0, \end{ cases } src=https://huaweicloudobs.ahjxjy.cn/7EBEC2AF88D3FF6A7D57C8999D5373CC.png style=vertical-align: middle;/>
③
<img class=jc-formula data-tex=\varphi (x,y)=\begin{ cases } cosx,\quad 0\le x\le \pi ,\quad 0\le y\le 1 \\ 0, \end{ cases } src=https://huaweicloudobs.ahjxjy.cn/29D6AD50E45D3573F9DE71CAD6F55CB4.png style=vertical-align: middle;/>
④
<img class=jc-formula data-tex=h(x,y)=\begin{ cases } cosx,\quad 0\le x\le \pi ,\quad 0\le y\le \frac { 1 }{ 2 } \\ 0, \end{ cases } src=https://huaweicloudobs.ahjxjy.cn/48B065AA5303B7AEF546E4410570FD16.png style=vertical-align: middle;/>