不挂科搜题免费

问题:

The dog handlers learned before the searches that

选项

  • each search area contained three target scents.

  • there was actually no target scent in the search area.

  • some target scents may be labelled with a special mark.

  • their dogs were

  • xpected to

  • ind the scents of red paper.

  • 答案:

    C