单项选择题
Columbus had accomplished one of the most amazing and courageous（）in history.
A．performance B．feats C．events D．acts
单项选择题 Although his people did not（）his efforts, he kept trying.
单项选择题 If you think her experience is（）, we will employ her.
单项选择题 We were working（）time to get everything ready for the exhibition.
