一般来说,同一个体内牙根最长的是哪一组牙
A.上颌尖牙B.上颌双尖牙C.上颌磨牙D.下颌双尖牙E.下颌磨牙
参考答案:A
The dam was not strong enough to _____ the flood waters. The people living there had to remove from their houses.[ ]
A. hold down
B. hold back
C. hold off
D. hold on
堤岸防护工程可选用()。
A.坡式护岸
B.坝式护岸
C.墙式护岸
D.其他防护形式