农业推广沟通的要素。
参考答案：
传递者、接受者、信息、渠道、反馈、关系、环境。
It is probably easier for teachers than for students to appreciate the reasons why learning English seems to become increasingly difficult once the basic structures and patterns of the language have been understood．
局麻药中加入1：200000肾上腺素是指20ml药液中加入肾上腺素（）
A.0.1mg
B.0.2mg
C.0.3mg
D.0.4mg
E.0.01mg
