问题
选择题
The president was _____ a speech to senators _____ a group of armed young people burst into the hall [ ]
A. giving; as
B. making; when
C. delivering; while
D. speaking; when
答案
答案：B
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N2O4(g)+Q（Q>0） 在测定NO2的相对分子质量时，下列条件下测定结果最接近理论值的是