Crops such as peas or soybeans put important minerals back into the soil, ______ it ready for crops that need fertile soil.
Professor Smith, along with his assistants, _____on the Project day and night to meet the deadline.
He met his previous teacher ________ at abroad.
Tom, ______ yourself .Did you forget the school rules?
He is the only one of the students who ______a winner of a scholarship for three years.
Though having lived abroad for years, many Chinese still ______ the traditional customs.