Recently I received a letter from him, and _____ was a big surprise for me.[      ]

A. that

B. which

C. it

D. who

抽余液塔塔顶压力表故障导致加热炉联锁时，应要求仪表人员（）。

A、摘除加热炉联锁

B、摘除燃料气低压力联锁

C、尽快更换或者修复压力表

D、暂时摘除塔顶压力高联锁