粉料风送系统的氧含量控制在1%以下,正常值为()%。
A、0.08-0.09
B、0.06-0.07
C、0.05-0.06
D、0.01-0.02
参考答案:D
—Why are you so _____, Mei Mei?
—Because of the _____ news! I failed the test again! [ ]
A. frustrated, frustrated
B. frustrating, frustrating
C. frustrating, frustrated
D. frustrated, frustrating
决定了胚盘的中轴及头尾方向的结构是什么?