There was nothing that they could do______.

单项选择题—Have you found your pen yet —No, I am not sure______I could have done with it.

单项选择题Take this bag and______you can find enough space.

单项选择题—Will you be able to finish the job this week

单项选择题We watched carefully______the house.

单项选择题—All the people in this village have black hair. —Yes, they all______each other.