| 21. | a trail of mucus left by a snail or slug |
| 蜗牛或蛞蝓留下的黏液痕迹
|
| 22. | pick up a trail , a scent |
| 发现踪迹, 察出气味
|
| 23. | trail a criminal, a wild animal |
| 追踪罪犯, 野兽
|
| 24. | tourists who leave a trail of litter everywhere they go |
| 一路走一路乱扔垃圾的游客
|
| 25. | a trail throughthe forest |
| 穿过森林的小路
|
| 26. | a trail of slime |
| 蜗牛的黏液痕迹
|
| 27. | blazing a trail in the field of laser surgery |
| 在激光外科手术领域中开拓新路
|
| 28. | trail one 's rival |
| 落后于对手
|
| 29. | trail one's coat |
| 寻衅
|
| 30. | blaze a [the ] trail |
| （在森林中）在树上刻出指路的标志；开辟道路；带头
|