柳石混厢的特点是什么？
参考答案：
施工速度快，坯间不打桩，柳石混合压厢，每坯均系于坝顶，不易发生前爬。
Survival craft EPIRBs (Class S) are（）.
A.permanently mounted in the survival craft
B.portable and stowed for carriage to the survival craft
C.permanently mounted on the bridge wings
D.portable and stowed in the emergency gear locker
以下哪类腺体的分泌方式属于顶浆分泌型（）
A.汗腺
B.皮脂腺
C.乳腺
D.唾液腺
E.肠腺
