钢的晶粒增长到一定程度后，机械性能降低，这种现象是（）。
A、过烧
B、脱碳
C、氧化
D、过热
参考答案：D
Although he sometimes loses his temper, his students like him＿＿＿＿＿for it.
A．not so much
B．not so little
C．no more
D．no less
A型人参皂苷的苷元是
A．人参二醇B．20(S)-原人参二醇C．齐墩果酸D．人参三醇E．20(S)-原人参三醇
