The drug improved mental alertness.该药有助于提神。Alertness, calmness, courage : he could see them all in the youngster's face.机警, 镇定, 胆量,都摆出在这年青人的脸上.We must maintain a military standard, an alertness, and never vary it.我们...

n.警戒，机敏，戒心...

alertness的音标：alertness的英式发音音标为：[ə'lɜ:tnəs]alertness的美式发音音标为：[ə'lɜtnəs]...