如下颌双侧第二乳磨牙拔除后,其缺隙保持器不宜选择()
A.舌弓保持器
B.活动保持器
C.丝圈式保持器
D.托牙保持器
E.固定桥保持器
参考答案:E
一个滑动变阻器上标有“20Ω 1.5A”的字样,它表示这个变阻器的____是20Ω,允许通过的____是1.5A。滑动变阻器应____联在需要调节电流大小的电路中,连入电路的滑动变阻器在电路闭合前,应将滑片P放在____的位置上。
Golf is rapidly becoming more popular. Near some towns and cities new courses are being built in ________.
A.what is farmland
B.what farmland is
C.what farmland was
D.what was farmland