Which of the following is NOT true about the attack at the fuel tanks a. The large fuel tanks were broken. b. It was an obvious terrorist attack. c. Nobody was injured or killed. d. The attackers tried to explode the tanks at about the same time as they blasted the hotels.

钢结构安装中的焊缝检测数量，以结构单元，每（）为一验收批。

A.三柱节

B.四柱节

C.一柱节

D.二柱节