______ retire are still able to receive pension that they have paid into the social security system during their working days.

To find out how the bees managed to tell time, an unusu...

单项选择题To find out how the bees managed to tell time, an unusual experiment was _______ four years ago.

An Olympic runner wins a _______.A．medal B．model C．mod...

单项选择题An Olympic runner wins a _______.

Within days he became paralyzed, and people feared that...

单项选择题Within days he became paralyzed, and people feared that he might die. But he _________.