根据勾股定理，AC=BD=
| AB2+BC2 |
| 22+32 |
| 13 |
∵EF∥AC∥HG，
∴
| EF |
| AC |
| EB |
| AB |
∵EH∥BD∥FG，
∴
| EH |
| BD |
| AE |
| AB |
∴
| EF |
| AC |
| EH |
| BD |
| EB |
| AB |
| AE |
| AB |
∴EF+EH=AC=
| 13 |
∵EF∥HG，EH∥FG，
∴四边形EFGH是平行四边形，
∴四边形EFGH的周长=2（EF+EH）=2
| 13 |
故选：D．
A. | 10 |
| 13 |
| 10 |
| 13 |
| AB2+BC2 |
| 22+32 |
| 13 |
| EF |
| AC |
| EB |
| AB |
| EH |
| BD |
| AE |
| AB |
| EF |
| AC |
| EH |
| BD |
| EB |
| AB |
| AE |
| AB |
| 13 |
| 13 |