板柱体系是指钢筋混凝土（）和（）组成的结构。
参考答案：无梁楼板、柱
正常人体内含碘最高的器官是（）。
A.脑
B.肝
C.肾
D.心
E.甲状腺
The 12-foot low-velocity fog applicator（）.
A.has a spray pattern 12 feet in diameter
B.can be used in conjunction with both 1-1/2 inch and 2-1/2 inch all-purpose nozzles
C.has a 90°bend at its discharge end
D.has a screw thread end which connects to the all-purpose nozzle
