领导的有效性是领导者、被领导者和（）的函数。
A.环境因素
B.经济因素
C.政治因素
D.情景因素
参考答案：D
患者男，20岁，寒战、高热10天，咳嗽，少许脓痰，血WBC18×109/L，X线胸片可见多个模糊小片影，伴一侧胸腔少量积液，病前右手曾有疖肿，对确定诊断最有意义的检查是( )
A．痰涂片革兰氏染色镜检B．痰、血细菌培养C．纤支镜检查D．血清抗体检测E．肺CT扫描
The boys and girls are often asked ______ loudly in the library. [ ]
A. not to speak
B. not speak
C. to speak
D. don't speak
