What did he _____ at the meeting? [ ]
A. say
B. speak
C. talk
D. tell
答案:A
CTCS-2级列控系统地面设备当LEU处于远程模式时,绿色LED灯以()的频率闪光。
A.1Hz
B.2Hz
C.3Hz
D.4Hz
因为1不是质数,所以14和1不是互质数.______.