Higher use of the passive voice is often viewed as an indicator of 'indirect' and more easily confused speech because the doer of the action is obscured.
过多使用被动语态的演讲通常被认为是传递了间接的、容易令人困惑的信息，因为施动者不明确。
2
The author tries to explain the limitation of passive input and the four reasons of pragmatic failures: pragmatic structure of discourse, speech rules, politeness strategy and indirect speech act.