What is the difference between 連用形 'て-form' and the い-stem?


If they are the same syntactically, why is it right to say 食べている but not 食べいる?
Why is it right to say 食べ続ける, but not 食べて続ける? Forgive my ignorance on this
topic.




The te-form and the masu-stem (aka i-form) are **not** the same syntactically.
There are [cases where they seem
interchangeable](https://japanese.stackexchange.com/q/23789/5010), but in most
cases, they are simply different. For example, only the masu-stem can [work as
a noun](https://japanese.stackexchange.com/a/32311/5010). You must use the te-
form before a subsidiary verb (eg 飛んでくる, 歩いてみる), and you must use the masu-
stem in a compound verb (eg 飛び出す, 歩き始める).

In English, gerunds and infinitives sometimes seem interchangeable. "I like to
play tennis" and "I like playing tennis" have the same meaning. But you can
say "I want to play tennis" but not "I want playing tennis". It's simply
because gerunds and infinitives are syntactically different.

When joining two clauses, 連用形 sounds [more formal and
literary](https://japanese.stackexchange.com/a/70324/5010). For other uses of
連用形, please see: [Do I have a good grasp on the basics of what the
continuative form is?](https://japanese.stackexchange.com/q/65936/5010)




The te-form and the masu-stem (aka i-form) are **not** the same syntactically.
There are [cases where they seem
interchangeable](https://japanese.stackexchange.com/q/23789/5010), but in most
cases, they are simply different. For example, only the masu-stem can [work as
a noun](https://japanese.stackexchange.com/a/32311/5010). You must use the te-
form before a subsidiary verb (eg 飛んでくる, 歩いてみる), and you must use the masu-
stem in a compound verb (eg 飛び出す, 歩き始める).

In English, gerunds and infinitives sometimes seem interchangeable. "I like to
play tennis" and "I like playing tennis" have the same meaning. But you can
say "I want to play tennis" but not "I want playing tennis". It's simply
because gerunds and infinitives are syntactically different.

When joining two clauses, 連用形 sounds [more formal and
literary](https://japanese.stackexchange.com/a/70324/5010). For other uses of
連用形, please see: [Do I have a good grasp on the basics of what the
continuative form is?](https://japanese.stackexchange.com/q/65936/5010)

