渤海海域发现的石油其芳香烃含量一般为（）
A、1%～5%
B、5%～10%
C、10%～30%
D、5%～10%
参考答案：C
Discourse theory of second language acquisition was developed from the______.
A．habit formation theory
B．Hallidays theory of first language acquisition
C．monitor theory
D．Cognitive theory
