The millions of calculations involved, had they been done by hand, all practical value by the time they were finished __________.

单项选择题According to the American federal government, residents of Hawaii have the longest life ______ 77.2 years.

单项选择题In order to recover their share of the world market, U.S. auto makers are （）

A．improving product quality
B．modernizing product style
C．repositioning their product in the market
D．increasing product features