单选题

There are seven questions below，

Acircus hasseven fenced enclosures, numbered 1 through 7, for two animals: a lion and a tiger. Each enclosure is connected to adjacent enclosures by interior gates.There are exactly eight such gates, each connecting one enclosure to exactly one other enclosure: enclosure 1 is connected to enclosures 2, 3 and 4; enclosure 3 to enclosures 1, 2, 4, and 5; and enclosure 5 to enclosures 3, 6, and 7. These gates provide the only connections between enclosures. Occasionally a trainer moves the animals. Taking either animals from one enclosure to an adjacent enclosure through a gate is called a "transfer." The following conditions are strictly observed:

There are seven questions below，

The two animals cannot be together in any enclosure or gate.

Transfers cannot occur simultaneously In moving either one animal or both to a specified enclosure or enclosures, theminimumnumber oftransfers needed to achieve the specified result are used.

单选题

If the lion is in enclosure 1 and the tiger is in enclo- sure 3, and the lion isto be moved to enclosure 7, the tiger could be in which of the following enclosures when all of the transfers have been completed?

A、 1
B、 3
C、 4
D、 5
E、 6

【正确答案】 C

【答案解析】

单选题

If the tiger is in enclosure 5 and the lion is in enclo- sure 3, moving the tiger to which of the following enclosures requires exactly two transfers?

A、 2
B、 3
C、 4
D、 6
E、 7

【正确答案】 B

【答案解析】

单选题

If the lion is in enclosure 6 and the tiger is in enclo- sure 7, and the lion isto be moved to enclosure 7 and the tiger to enclosure 6, then which of the following must be true?

A、 The lion is transferred to enclosure 3 at some time during the move.
B、 The tiger is transferred to enclosure 5 twice.
C、 One of the two animals is transferred to enclosure 3 twice.
D、 Three transfers to enclosure 5 are made.
E、 At least one transfer is made to either enclosure 2 or enclosure 4.

【正确答案】 D

【答案解析】

单选题

If the lion is in enclosure 3 and the tiger is in enclo- sure 4, and the lion isto be moved to enclosure 5 and the tiger to enclosure 7, then exactly how many transfers must be made?

A、 Four
B、 Five
C、 Six
D、 Seven
E、 Eight

【正确答案】 C

【答案解析】

单选题

If the lion is in enclosure 1 and the tiger is in enclo- sure 7, and the lion isto be transferred to enclosure 3 and the tiger to enclosure 1, then which of the following CANNOT be true?

A、 The lion is transferred to enclosure 2 in the first transfer.
B、 The lion is transferred to enclosure 3 in the second transfer.
C、 The lion is transferred to enclosure 4 in the second transfer
D、 The tiger istransferred to enclosure 5 in the first transfer.
E、 The tiger is transferred to enclosure 3 in the second transfer.

【正确答案】 B

【答案解析】

单选题

If the lion isin enclosure 1 and the tiger isin enclo- sure 3, and the lion isto be moved to enclosure 6 and the tiger to enclosure 5, then the second transfer could be a transfer of the

A、 lion to enclosure 2
B、 lion to enclosure 5
C、 tiger to enclosure 4
D、 tiger to enclosure 5
E、 tiger to enclosure 7

【正确答案】 E

【答案解析】

单选题

If the lion is in enclosure 3 and the tiger is in enclo- sure 6, and the lion isto be moved to enclosure 6 and the tiger to enclosure 3, then which of the following must be true?

A、 Exactly five enclosures are used in the move
B、 One animal is transferred exactly twice as many times as the other animal.
C、 All of the transfers of the lion are completed before any transfer of the tiger occurs.
D、 At one point one of the animals is transferred to either enclosure 2 or enclosure 4.
E、 At one point neither the lion nor the tiger is in enclosure 3, enclosure 5, or enclosure 6

【正确答案】 B

【答案解析】