奧數網小升初英語天天練欄目每日精選一題，定期選擇不同類型題提供給學生，本期題型主要為：選擇題
·本周試題由學而思樂加樂名師高麗偉精選、解析，以保證試題質量。
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1、Did you know? In the decimal number system (base 10) ten different digits, 0 to 9, are used to write all the numbers. In the binary number system (base 2) two different digits are used, i.e. 0 and 1.
Which one of the following numbers is not a valid number in the
octal number system (base 8)?
A) 128 B) 127 C) 126 D) 125 E) 124
2、The number of diagonals that can be drawn in a regular polygon with
twenty sides (icosagon) is_____.
3、If a and b are integers, 10??3=1,152??7=3, and then 379??6 is equal to_____.
4、Two numbers are in the ratio 2 : 3. When 4 is added to each number the ratio changes to 5 : 7.The sum of the two original numbers is____.
5、The greatest number of Mondays which can occur in 45 consecutive
days is____
6、Saul plays a video game in which he scores 4 for a hit and lost 6 for a miss. After 20 rounds his score is 30. The number of times he has missed is____.
7、Three girls A, B and C run in a 100 m race. When A finishes, B is 10 m
behind A and when B finishes C is 20 m behind B. How far in metres was C from A when A finished?(Let’s assume all the athletes run at a constant speed)
8、The areas of the faces of a rectangulabox are 84 cm2 , 70 cm2and 30 cm2.The volume of the box in cm3 is____.
9、You have 3 weights: 1 kg, 3 kg and 9 kg as well as an equal arm balance, as shown. How many different weight objects can you weigh with these three?
參考答案：
1、A 考察我們學過的簡單的進位問題，顯然8進位中沒有8出現
2、170 找規律，公式為n×(n-3)÷2
3、1 定義新運算，就是求379÷6的餘數。
4、40，16和24
5、7
6、5
7、28米，根據距離比求出速度比，三者的速度比為1：9/10：18/25
8、420 分解質因數
9、13種
名師介紹：
高麗偉老師 是樂嘉樂優秀專職教師。
教學特色
所教學生進步很快，尤其是單詞方面，不再有牴觸心理，學生背單詞記得牢，且口語水平顯著增強。所教學生多人獲得北京市級各項英語競賽獎項，20餘人考 入四中、人大附、北大附等重點中學，絕大部分學生經過一年以上的連續學習提分明顯。其中張同學去年順利考入人大附的點招考試，並在面試中表現優異，取得理 想成績。