問題詳情
5.已知{an}为等差数列， 
，则a20等于
(A). -1
(B). 1
(C). 3
(D).7
，则a20等于(A). -1
(B). 1
(C). 3
(D).7
參考答案
答案：B
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)
內容推薦
- The forest guards often find campfires that have not been ______ completely.(A) turned down (B)
- “a+c＞b+d”是“a＞b且c＞d”的(A). 必要不充分条件(B). 充分不必要条件(C). 充分必要条件(D). 既不充分也不必要条件
- 9．设函数 ，则f(x)：(A)．有最大值(B)．有最小值(C)．是增函数(D)．是减函数
- 8．函数 的图象的对称轴方程可能是：(A)． (B)． (C)． (D)．
- 4．a＜0是方程ax2+1=0有一个负根的：(A)．必要不充分条件(B)．充分必要条件(C)．充分不必要条件(D)．既不充分也不必要条件
- 3．已知m，n是两条不同的直线，α，β，θ是三个不同的平面，下列命题中正确的是：(A)．若α⊥γ，β⊥γ则α∥β(B)．若m⊥α，n⊥α则m∥n(C)．若m∥α，n∥α，则m∥n(D)．若m∥α，m∥
- 不等式组 所表示的平面区域的面积等于(A). 3/2(B). 2/3(C). 4/3(D). 3/4
- How does Ridley look at shopping?(A) It encourages the creation of things.(B) It results in shor
- 2．若 ，则 (A)．(1,1)(B)．(-1,-1) (C)．(3,7)(D)．(-3,-7)
- 63 DFeeling blue about world ? “Ceer up.” Says science writer Matt Ridley.”The world has never been
內容推薦
- _____you call me to say you' re not coming, I'll see you at the theatre.(A) Though (B)
- 5．在三角形ABC中，AB=5，AC=3，BC=7，则∠ABC的大小为：(A)． (B)． (C)． (D)．
- 10．若过点A(4,0)的直线l与曲线(x-2)2+y2=1有公共点，则直线l的斜率的取值范围为：(A)． (B)． (C)． (D)．
- (A) make up (B) 'connect with (C) control (D) explain
- (A) duty (B) effort (C) job (D) task
- "We can' t go out in this weather," said Bob, ______ out of the window.(A) lookin
- 下列何種聽力損失的聽閾值符合接受特殊教育的資格，但卻未能申請身心障礙手冊？(A)20 分貝 (B)45 分貝 (C)55 分貝 (D)60 分貝。
- 考察正方体6个面的中心，从中任意选3个点连成三角形，再把剩下的3个点也连成三角形，则所得的两个三角形全等的概率等于(A).1(B). 1/2(C). 1/3(D). 0
- 下列曲线中离心率为 的是(A). (B). (C). (D).
- (A) events (B) chances (C) feelings (D) moments
- 11．若A为不等式组 表示的平面区域，则当a从-2变化到1时，动直线x+y=a扫过A中的那部分区域的面积为；(A)．3/4(B)．1(C)．7/4(D)．2
- You ______ be tired - you've only been working for an hour.(A) must not (B) won' t (C)
- 直线l过点（-1，2）且与直线垂直，则l的方程是(A)．3x+2y-1=0(B). 3x+2y+7=0(C). 2x-3y+5=0(D). 2x-3y+8=0
- (A) for no reason (B) from a distance(C) by accident (D) as gifts
- (A) Instead (B) Normally (C) Certainly (D) Then
- I ______ you not to move my dictionary -- now I can' t find it.(A) asked (B) ask (C) was as
- When flint _______ to the market, these products enjoyed great success.(A) introducing (B) intro
- 6．函数f(x)=(x-1)2+1,(x≤0)的反函数为：(A)． (B)． (C)． (D)．
- (A) description (B) pointing (C) scene (D) talk
- (A) general (B) deep (C) personal (D) lively
- If you buy more than ten, they knock 20 pence off ______.(A) a price (B) price (C) the price (D)
- 7． ，则 中奇数的个数为：(A)．2(B)．3(C)．4(D)．5
- There were dirty marks on her trousers ______ she had wiped her hands.(A) where (B) which (C) wh
- (A) Surprisingly (B) Suddenly (C) Expectedly (D) Fortunately
- (A) Interested (B) Anxiously (C) Seriously (D) Encouraged