下列哪种电生理指标反映未用肌松药者麻醉出现过浅效果较好（）

A.脑电图

B.额肌电

C.食管下段括约肌收缩性

D.指端容积描记图

E.以上均是

One of the effective ways to lessen environmental pollution is the reservation and protection of more swamps.

A．vast thick corals

B．pockets of wetland

C．warm volcanoes

D．millions of bees and wasps