21. I have just heard ________ announcement on the radio that ________ new cure for this disease has been found out.
A. the; a B. an; / C. the; the D. an; a
【解析】选D。考查冠词用法。句意：我从收音机上听到一则通知，这种疾病的一种新的治愈方法已被发现。由句意可知两个空格处都表示泛指，故选D。
22. My computer began to return to the ________ running state after I killed the virus by newly-updated Kill 3, 000.
A. normal B. ordinary
C. usual D. common
【解析】选A。考查形容词词义辨析。return to the normal running state意为“恢复到正常的运行状态”。ordinary普通的；usual通常的；common常见的。normal正常的，符合句意。
