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正确答案/Answer:A

Solution: Each path has only horizontal and vertical segments. The total length of the horizontal segments is the same for each path. So it is enough to compare the total length of the vertical segments. Option A has the shortest path.

解析：每条路径仅包含水平与垂直段。水平段总长度相同，因此只需要比较垂直段的总长度。选项 A 的路径最短。

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正确答案/Answer:C

Solution: 1, 2, 3, 4, 5, 6, 7 are the numbers to fill in. 6 is already there. Below the 6, the sum should be higher than 6, so that could only be the 7. The 7 is now at the bottom left circle. We have to find the answer for 6 + ... = 7, so, this could only be 1. We now have left 2, 3, 4, 5. The two highest numbers should be sums, so, go in the bottom row. The 4 cannot be formed with summing a pair out of 2, 3, or 5. Therefore, the 4 has to come from 1 + ... = 4. This gives the position of 4 in the bottom middle, which is the correct answer (the star), and the 3 in the top. Then, the 5 is on the bottom right, and 2 on the top right.

解析：1、2、3、4、5、6、7是要填入的数字，其中6已经填好。在6的下方，所填数字之和应大于6，因此只能是7。7现在在左下角的圆圈中。我们需要找到 6 + … =7 的答案，所以只能是1。现在剩下2、3、4、5。两个最大的数字应作为和放在底行。4 无法由2、3或5中的任意两个数字相加得到，因此4必须来自 1 + … =4。这确定了 4是正确答案，填在底行中间的星形位置；3填在顶部；然后5填在底行右侧，2填在顶部右上角。

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正确答案/Answer:B

Solution:The first 5 plugs get 1.6 L each. The three plugs on the left side have in total 4.8 L. These 4.8 L are divided into two new plug, that is 2.4 L in each. The two plugs on the right have 1.6 L each. So, in container B it will get 2.4 L + 1.6 L = 4 L.

解析：通过前 5 个塞孔各流出 1.6 升 。通过左侧三个塞孔共流出 4.8 升，这些水被均分到两个新塞孔，每个塞孔流出 2.4 升。右侧两个塞孔各流出 1.6升。因此，容器 B 将得到 2.4 升 + 1.6 升 = 4 升。

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正确答案/Answer:B

Solution (解析): 90 − 62 = 28; 28 + 42 + (90 − x) = 180 − 90; x = 70

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正确答案/Answer:D

Solution:To remove the brick N4 we need to remove the first row of bricks (N1 and N2). So we’ll need 3 moves.

Case 1. We remove brick N1( Probability P=1/2). Then N2 will have to go ( P=1/2 ). To have N4 removed we have a chance of P=1/3. So the probability for this case is 1/2 · 1/2 · 1/3 = 1/12.

Case 2. Because of the symmetry the same happens if we remove brick N2 first. Since the events are exclusive the answer is 1/12 + 1/12 = 1/6 .

解析：为了移除砖块 N4，我们需要先移除第一行的砖块（N1 和 N2）。因此，我们需要 3 步。

情况 1 ：我们移除砖块N1 ( 概率 P=1/2 )。那么 N2 将不得不被移除( P=1/2 )。为了移除 N4，我们有 P=1/3 的机会。因此，这种情况的概率是 1/2 · 1/2 · 1/3 = 1/12。 情况 2 :由于对称性，如果我们先移除砖块 N2，后续情况相同。 由于这些事件是互斥的，所以答案是 1/12 + 1/12 = 1/6。

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正确答案/Answer:B

Solution: Each kangaroo changes the color of their square each turn. Since they start on two different colors, there must be at least two squares with kangaroos after each turn, so at most 14 squares can be empty. 14 empty squares is possible: for example all the kangaroos from black squares can go to the bottom left corner and all the kangaroos from white squares to the bottom right corner. This is possible since the number of jumps is even.

解析：每只袋鼠每回合都会改变其所在格子的颜色。由于它们起始于两种不同颜色的格子，每回合后至少有两个格子有袋鼠，所以最多可以有 14 个空格子。14 个空格子是可能的：例如，所有来自黑色格子的袋鼠都跳到左下角，所有来自白色格子的袋鼠都跳到右下角。由于跳跃次数是偶数，这是可以实现的。