The manager of a horse show is placing seven obstacles-one chicken coop， one gate， two stone walls， and three fences-on a jumping course that consists of seven positions， numbered and arranged consecutively from 1 to 7. The placement of the obstacles in the seven positions must conform to the following conditions：

No two fences can be placed in consecutive positions.The stone walls must be placed in consecutive positions.

1. Which of the following is an acceptable placement of obstacles in the seven positions，in order from the first position to the last position on the course？

（A） Chicken coop， fence， gate， stone wall， fence，stone wall， fence

（B） Fence， gate， fence， fence， chicken coop，stone wall， stone wall

（C） Fence， stone wall， stone wall， gate， chickencoop， fence， fence

（D） Gate， stone wall， stone wall， fence， fence，chicken coop， fence

（E） Stone wall， stone wall， fence， chicken coop，fence， gate， fence

2. If one of the fences is in the third position and another is in the sixth position， which of the following must be true？

（A） The chicken coop is in the seventh position.

（B） The gate is in the second position.

（C） The gate is in the seventh position.

（D） One of the stone walls is in the first position.

（E） One of the stone walls is in the fourth position.

3. If one of the stone walls is in the seventh position，which of the following must be FALSE？

（A） The chicken coop is in the second position.

（B） The chicken coop is in the fourth position.

（C） One of the fences is in the first position.

（D） One of the fences is in the second position.

（E） The gate is in the fourth position.

4. Which of the following CANNOT be the positions occupied by the three fences？

（A） First， third， and fifth

（B） First， third， and sixth

（C） Second， fourth， and sixth

（D） Second， fourth， and seventh

（E） Third， fifth， and seventh

5. If a stone wall is placed immediately after the gate， which of the following is a complete and accurate list of the positions in which the gate can be placed？

（A） Second， third （B） Second， fourth

（C） Third， fourth （D） Second， third， fourth

（E） Third， fourth， fifth

6. If the chicken coop is not placed immediately after any fence， which of the following is a complete and accurate list of the positions in which the chicken coop can be placed？

（A） First， second， third

（B） First， third， fourth

（C） First， fourth， sixth

（D） First， second， third， fourth

（E） First， third， fourth， sixth

答案：EED CBE