问题 解答题
给出命题p:方程
x2
a
+
y2
2-a
=1表示焦点在y轴上的椭圆;命题q:曲线y=x2+(2a-3)x+1与x轴交于不同的两点.
(1)若命题p是真命题,求a的取值范围;
(2)如果命题“p∨q”为真,“p∧q”为假,求实数a的取值范围.
答案

(1)若命题p为真,则有

a>0
2-a>0
2-a>a

解之得0<a<1,即实数a的取值范围为(0,1);

(2)若命题q为真,则有

△=(2a-3)2-4>0,解之得a

1
2
或a
5
2

∵命题“p∨q”为真,“p∧q”为假

∴p、q中一个为真命题,另一个为假命题,

①当p真q假时,

0<a<1
1
2
≤a≤
5
2
,得
1
2
≤a<1;

②当p假q真时,

a≤0或a≥1
a≤
1
2
或a≥
5
2
,得a≤0或a
5
2

所以a的取值范围是(-∞,0]∪[

1
2
,1)∪[
5
2
,+∞).

完形填空
完形填空。
     One of David's friends loved money very much, and   1   gave anything to anybody. Soon he became   2  .
     One day, he was   3   near the river with his friends when he slipped (滑倒) and fell in. His friends ran
to help him. And one of them held out his hand and said, "  4   me your hand, and I will pull (拉) you out."
The rich man's head went under the water and then came up again,   5   he didn't give his hand. Again another
of his friends tried but again the   6   thing happened.
     Then David said, "  7   my hand, and I will pull you out!" The rich man took his hand and David pulled
him   8   of the water.
     "You don't know our friend very well," he said to the   9  . "When you say 'give' to him, he does  10  , but
when you say 'take', he takes at once."
( )1. A. always    
( )2. A. good      
(     )3. A. walking   
( )4. A. Take      
( )5. A. but       
( )6. A. different 
(     )7. A. Get       
( )8. A. from      
( )9. A. other     
( )10. A. something
B. never 
B. poor  
B. walks 
B. Get   
B. or    
B. same  
B. Hold  
B. up    
B. another
B. nothing
C. sometimes
C. rich     
C. walk     
C. Hold     
C. then     
C. other    
C. Give     
C. out      
C. others   
C. everything
D. not    
D. bad    
D. walked 
D. Give                         
D. and    
D. worst  
D. Take   
D. down   
D. ones   
D. anything
解答题