The development of industry has been ______ gradual process throughout ______ human existence, from stone tools to modern technology.
_____ the help of experienced career instructors, this type of job-hunting training ____ to be very efficient.
Music should be taught routinely in schools because of the benefits ______ can have on the development of the brains of young children.
—You didn’t go to Europe, why? —I _____ this morning, but I _____ to Shanghai because of an emergency .
The lady has an abnormal state of mind. Whatever happens, she always assumes ______.
Car lovers often organize field sports in our country. It is an activity that they ______ without the benefits of a car.