() for your help, we’d never have been able to get over the difficulties.

单项选择题The Internet has brought () big changes in the way we work.

A. about
B. out
C. back
D. up

单项选择题Between 65,000 and 35,000 years ago, ().

A. the temperature changed a lot
B. the earth was much warmer than it is now
C. winter isn’t colder than summer
D. most of the ice that melted was in the Northern hemisphere during the 30,000-year long ice age