vừa ... vừa ...

Structure: Subject + vừa + [Verb/Adjective Phrase 1] + vừa + [Verb/Adjective Phrase 2]

1. Simultaneous Actions (While Doing)
Use it with verbs to mean doing two things at once. The two actions are coordinate and grammatically equal, meaning their order is often completely interchangeable: vừa đi vừa hát or vừa hát vừa đi (walking while singing). It can link entire verb phrases, not just single words (e.g., Tôi vừa đi học vừa đi làm - I both study and work). Note that the subject is only stated once at the beginning; do not repeat the subject after the second vừa.

2. Co-existing Qualities (Both... And...)
Use it with adjectives to describe two qualities of the same thing. These traits can be harmonious or contrasting. Using it for contrasting traits (e.g., vừa đắt vừa ngon - both expensive and delicious) is perfectly acceptable and commonly used to emphasize that two unexpected qualities exist simultaneously. While native speakers frequently mix contrasting traits for emphasis, some strict grammar textbooks teach that the adjectives must be both positive or both negative.

3. With Nouns
In everyday usage, you cannot attach vừa directly to nouns. You must use vừa là [Noun 1] vừa là [Noun 2]. However, the là can be dropped in certain fixed idioms or poetic contexts (e.g., vừa thầy vừa thợ - both teacher and worker).

4. Negative Form (Neither... Nor...)
To say 'neither... nor...', the standard and much more natural way is to use không ... cũng không .... While vừa không [A] vừa không [B] is grammatically possible, it is less common.

Important Notes:
• Single Subject & Omission: This pattern is used when there is a single shared subject. If two different people are doing two different things, use trong khi. Note that due to subject omission, the subject can be dropped if understood from context.
• Added Emphasis: Native speakers frequently use the variation vừa ... lại vừa ... for extra emphasis when chaining verbs or adjectives (e.g., vừa bổ ích lại vừa tiện lợi - both useful and convenient).
• Tense Markers: Tense markers like đang or sẽ often go before the first vừa (e.g., Tôi đang vừa ăn vừa xem TV - I am eating while watching TV), but they can also be placed after it (e.g., Tôi vừa đang ăn vừa đang xem TV - I am eating while watching TV).
• Chaining Multiple Items: It is possible to chain three or more items together for heavy emphasis (e.g., Quán này vừa rẻ, vừa ngon, vừa nhiều - This restaurant is cheap, delicious, and gives large portions).
• Rule of Parallelism: Generally, the two elements should be parallel (the same part of speech). While mixing verbs and adjectives is sometimes acceptable (e.g., vừa đẹp vừa hát hay - both beautiful and sings well), you should avoid mixing verbs with nouns. For example, saying vừa đi học vừa là nhân viên (both studying and being an employee) is clunky compared to keeping them parallel like vừa đi học vừa đi làm (both studying and working).
• Do not drop the second vừa: A single vừa before a verb means 'just/recently', which is often expanded to vừa mới (e.g., Tôi vừa mới ăn - I just ate). Also, do not confuse this with vừa ... đã ..., which means 'no sooner than' or 'as soon as [A] happened, [B] already happened' (e.g., Tôi vừa về đến nhà đã mưa - It rained as soon as I got home).