禽黄曲霉毒素中毒的特征性病变在（）。 A.肝脏 B.肠道 C.脑 D.心 E.肾脏

The experts were doing their experiment in the lab, ______ what happened outside. [ ]

A. didn't know

B. not knew

C. not knowing

D. having not known

Annie Jump Cannon, ________ discovered so many stars that she was called "the census taker of the sky".

A．a leading astronomer,

B．who, as a leading astronomer,

C．was a leading astronomer,

D．a leading astronomer who

当尿中尿胆原、尿胆素完全阴性时，应考虑（）。

A.肝细胞性黄疸

B.阻塞性黄疸

C.溶血性黄疸

D.药物性黄疸

E.肠梗阻

公路按技术等级分，可分为（）等级。

A、高速公路

B、国道

C、省道

D、一级公路

E、二级公路

判断热风炉燃烧器燃烧是否充分的依据有火焰颜色及状态、出口氧含量、和出口CO含量无关。