In America, if__________friend has invited you to drop by anytime, it is__________best to call before visiting to make sure it is convenient for him.
He won’t wear a hat _____.
It was not until mid-night _____ he went back home after the experiment.
I don’t know why she suggested that we _____ the work before dark.
— _____ for the glass! —It’s OK. I’m wearing shoes.
The bell rang and came in Mr. Brown, _____ a book in his hand. Then the class began.