腰麻平面达T₄，心率减慢的主要原因是（）

A.支配心脏交感神经节前纤维阻滞

B.血压下降

C.右房压下降

D.窦弓反射

E.肾上腺素能神经纤维阻滞

Nuclear science should be developed to guard peace ____ destroy the world.

A．instead of

B．more than

C．rather than

D．less than