若患者两侧同时多数牙缺失，义齿连接方式可采用（）
A．间隙卡环
B．单臂卡环
C．长臂卡环
D．对半卡环
E．三臂卡环
参考答案：A
电气工具和用具应由专人保管，每（）须由电气试验单位进行定期检查。
Attempts have been made for nearly three decades to increase the amount of precipitation from clouds by seeding them with salt or silver iodide. ()
A. Devices
B. Hypotheses
C. Efforts
D. Suggestions
