Active voice expresses the subject as the doer of the action and is the basic sentence pattern in everyday Chinese narration. In spoken and written language, active sentences are typically concise and direct. Active voice is suitable for narrating one's experiences, plans, and opinions. The active construction can flexibly combine with time, place, and other elements to add information.

Passive voice emphasizes that the subject is affected by an action or result, often expressed with the '被' construction. Passive structures are common when describing results, receiving handling, or when the agent is not convenient to specify. In written language and formal contexts, passive expressions are also used to explain processes or regulations. Passive sentences typically include '被', but there are implicit passives that do not use '被'.

Formal occasions include work, school, notices, official documents, and communication with elders or superiors. Formal expressions emphasize completeness, objectivity, and politeness, often using written vocabulary and standard structures. Formal contexts tend to avoid colloquialisms and filler words. Formal expressions typically use connectors and phrases such as 'Please', 'Due to', and 'Therefore' to connect and explain.

Informal settings include everyday conversations among friends, family, and acquaintances. Informal expressions are more colloquial, sentences can be shorter, and mood particles are commonly used to add friendliness. In informal contexts, some components can be omitted as long as the meaning is clear. Informal expressions freely use common spoken vocabulary.

Polite expressions in Chinese are reflected through word choice and sentence structure, especially in formal settings. Common honorific terms include '您' (you, formal), '请' (please), '麻烦' (to trouble), '劳驾' (excuse me). Using polite sentence forms in requests and assignments is more appropriate than direct commands. Politeness terms are often added when thanking or troubling others.

Written language commonly uses standard vocabulary and structures, with precise semantics to avoid ambiguity. Written language tends to use nominalizations and logical connectors. Written language is common in notices, reports, and explanatory texts. Written language typically reduces exclamations and colloquial elements.

Colloquial speech tends to use common high-frequency verbs and simple structures, with direct expression. It often uses sentence-ending particles to add emphasis or convey attitude. Colloquial speech frequently includes repetition or supplementation, aligned with conversational habits. It emphasizes communicative efficiency and allows some omission.

In Chinese spoken language and informal writing, omission of known information is often used to enhance coherence. In dialogues, subjects, objects, or times are often omitted as long as the context is clear. Formal writing tends to retain complete components to ensure clarity. Omission is not a syntactic error but a discourse choice.

Whether to use formal or informal expression depends on the conversation partner, setting, and communication purpose. Use formal expression with superiors, strangers, or in formal documents. For friends, family, or private chats, informal expressions can be used. Switching styles is an important strategy for efficient communication.