—You were not listening；what troubled you?

—I         my coming math exam．

A．am thinking about

B．was thinking about

C．had thought about

D．will think about

生物学的特点因素除了有遗传因素，年龄、性别因素，爱好因素还有（）。

A、基因因素

B、繁衍因素

C、个人因素

D、性格、情志因素