特种作业人员必须持证上岗，并佩戴相应的劳保。

若P（2，1）为圆（x-1）²+y²=25的弦AB的中点，则直线AB的方程为______．

Not only ______, but Hunan TV’s reality show, Dad, Where Are We Going, also has made the stars and their lovely kids more popular.

A．it has received one-sided praise

B．has it received one-sided praise

C．it receives one-sided praise

D．does it receive one-sided praise

下列对心交感神经的叙述，错误的是

A．节后纤维释放的递质是去甲肾上腺素

B．可导致心率加快

C．可导致房室交界的传导加快

D．可导致心房和心室肌收缩力加强

E．肾上腺素受体可阻断其作用

CNC系统系统软件存放在()。

A、单片机；

B、程序储存器；

C、数据储存器；

D、穿孔纸带

蜜蜂螨虫感染可用双甲脒灭螨虫，但不宜用抑除虫菊酯杀灭螨与其卵。