意识水平下降的意识障碍包括（）

A.意识模糊

B.昏迷

C.昏睡

D.嗜睡

E.谵妄

From the symptoms shown in the dead body, he ________to death by a certain poisonous chemical,

but I can't tell exactly which. [ ]

A. must have been poisoned    

B. should have been poisoned

C. could have been poisoned      

D. may have been poisoned