.— When did they come back last night?— It was midnight ____ all of us were sleeping.
His physical disability makes _____ rather difficult for him to find a good job.
After some time in the dark cave, our eyes slowly _____ the dark.
---Did the little boy manage _____ the suitcase upstairs? ---No, he didn’t. He isn’t strong enough even ______ it.
______ the workers’ working conditions, the boss will allow them to have a coffee break.
My friend David was not used _______ by air, so he felt unwell(不舒服).