A:described; wouldn’t waste
B:had described; wouldn’t have wasted
C:would have described; had wasted
D:described; wasted
火箭常用联氨(N2H4)作燃料,反应的化学方程式为:N2H4+2NO2X+2H2O.则X的化学式是( )
在很多时候,医生对患绝症的病人仍满脸笑容,轻声告诉他们:“没事的,如果你与我们配合将很快好起来的。”可见,善意的谎言:( )