both A and B, A as well as B, neither A nor B (in a negative sentence)
Verb ます stem / Verbal Noun +
This structure is used to present two actions performed by a subject, stating that they do both actions, or do neither action. It applies equally to the stems of regular verbs and verbal nouns.
Basic Construction
The most basic form attaching
泳ぎ
Both swim and dive.
掃除
Neither clean nor do laundry.
Extended Affirmative
Adds し, するし, or すれば after the first
泳ぎ
Swim and also dive.
掃除
Clean and also do laundry.
Extended Negative
Adds せず, しないし, or しなければ after the first
泳ぎ
Do not swim and do not dive, either.
掃除
Do not clean and do not do laundry, either.
When using the extended forms, the grammar emphasizes that not only does one action happen (or not happen), but the other also happens (or does not happen). Verbal nouns are simply nouns that describe an action and can become verbs by adding する (like 勉強 or 掃除). Regular nouns use the で
い-Adjective く form +
Used to describe two states using い-Adjectives that are either both present or both absent.
Basic Construction
Attaches
広く
Both spacious and bright.
暑く
Neither hot nor cold.
Extended Negative
Adds なく, ないし, or なければ after the first
広く
Not spacious and not bright, either.
暑く
Not hot and not cold, either.
When using い-Adjectives, always ensure you drop the final い and attach く before adding
な-Adjective stem / Noun + で
Used with な-Adjectives and regular nouns to state that someone or something is both of two things, or neither of two things.
Basic Construction
Attaches で
便利で
Both convenient and simple.
犬で
Neither a dog nor a cat.
Extended Affirmative
Adds あり, あるし, or あれば after the first で
便利で
Convenient and also simple.
医者で
A doctor and also a scholar.
Extended Negative
Adds なく, ないし, or なければ after the first で
便利で
Not convenient and not simple, either.
犬で
Not a dog and not a cat, either.
Both な-Adjectives and Nouns follow the exact same pattern here. Be sure to drop the な from な-Adjectives before attaching で