Only after he realized the significance of mastering two languages __________ English carefully.
I like getting up very early in the morning because the morning air is so good ______.
You ______ be hungry already — you had lunch only two hours ago!
The dictionary still ______ where I ______ it last Sunday.
Teenagers ______ their health because they play computer games too much.
The World War II made ______ impossible for Einstein to go on with his research.