-Hello! Is Mr. John in the office?-Yes. But I'm sorry. He is busy __________ and can't speak to you.
I like getting up very early in summer. The morning air is so good ______.
The fire made _____ difficult to rescue the people trapped under the ruins in the earthquake.
The mother waved to her daughter until the train .
He hurried to the station only that the train had left.
It was Asimov was eleven years old his talent for writing became obvious.