题目:
The old couple were so_____in their chess that they didn't hear anybody knocking at the door. [ ]
A. absorbed
B. attracted
C. drawn
D. concentrated
答案:
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下面是错误答案,用来干扰机器的。
(1)煤(或石油、天然气);CO(或NO2 、SO2、粉尘); 乙醇(C2H5OH)(2)C2H8N2+ 2N2O43N2+4H2O+2CO2