____paragraph is a group of sentences about some related subject. Readers must know what the main idea of ___paragaph is in order to understand ___information they are reading.

A．The ,a ,the

B．A,the ,the

C．A,a the

D．The ,the ,the

属于负反馈调节的是

A．排尿反射

B．减压反射

C．分娩

D．血液凝固

E．血液凝集