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【单选题】
( 2018• 衡阳)如图,抛物线 y=ax 2 + bx + c 与 x 轴交于点 A (- 1 , 0 ),顶点坐标( 1 , n )与 y 轴的交点在( 0 , 2 ),( 0 , 3 )之间(包含端点),则下列结论: 1 3a + b < 0 ; 2 - 1 ≤ a ≤ - ; 3 对于任意实数 m , a + b ≥ am 2 + bm 总成立; 4 关于 x 的方程 ax 2 + bx + c=n - 1 有两个不相等的实数根.其中结论正确的个数为( )A.
1个
B.
2个
C.
3个
D.
4个
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【单选题】— We expected you yesterday. — I’m sorry, I you to say that I couldn’t be here until today.
A.
must have called
B.
would be calling
C.
could have been calling
D.
should have called
【单选题】—— We expected you yesterday. —— I'm sorry, I______you to say that I couldn't be here until today.
A.
should have called
B.
must have called
C.
could call
D.
would call
【单选题】We expected that you ___________ (stay) here.
A.
stay
B.
stays
C.
will stay
D.
would stay
【简答题】Which term describes the behavior of materials when subjected to some external force or condition? A) Material B) Property C) Automation D) Synthesis
【简答题】如图，长方形OABC中，O为平面直角坐标系的原点，A、C两点的坐标分别为（3，0），（0，5），点B在第一象限内. (1)如图1，写出点B的坐标（ ）； (2)如图2，若过点C的直线CD交线段AB于点D,且把长方形OABC的周长分为3:1两部分,求点D的坐标； (3)如图3，将（2）中的线段CD向下平移2个单位,得到C / D / ,试计算四边形OAD / C / 的面积.
【简答题】在平面直角坐标中，已知A、C两点的坐标分别为A（ 5 ， 5 ）、C（ 3 5 ，0）． （1）求△OAC的面积． （2）在第一、二象限内是否存在点B，使以O、A、B、C为顶点的四边形为平行四边形？若存在，请求出所有符合条件的点B的坐标；若不存在，请说明理由．
【单选题】When is the normal force not equal to the weight of an object?
A.
In space where there is no gravity
B.
When the object is being accelerated upward
C.
When the object is on an inclined plane
D.
When the object is supported by a string
E.
When it is moving along a flat surface
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