下列属于微生物的一组生物是（ ） A．①②⑦ B．③④⑤ C．①⑤⑥ D．②⑥

As the College Entrance Examination is drawing nearby, some students would rather expect

good luck than to make every effort to study．They think success results good luck．Whether they can be admitted to key universities depend on luck．However, others insist that diligence is a mother of success．Only by working hard can they achieve what they want．Since they fail sometimes, they don’t give up, for they believe that success lies in our own hands．As for me, I’m in favor of the latter opinion．Luck doesn’t come alone．It goes hand by hand with hard working．Sometimes, some students are lucky enough to succeed, but such luck won’t last long because it is not basing on their own abilities．

按照国家规定，如果发生一次安全事故死亡14人属于______。

A．大事故

B．重伤事故

C．伤亡事故

D．特大伤亡事故

比例微分的英文缩写是（）

A．PI

B．PD

C．VR

D．PID

在流行病学研究中，选入到研究中的研究对象与没有被选入者特征上的差异所造成的系统误差是

A．报告偏倚

B．暴露怀疑偏倚

C．信息偏倚

D．选择偏倚

E．混杂偏倚

影响放大电路工作点稳定的主要因素是（）的变化。