The izenkei conjugation has only one function in modern Japanese. Combined with + ば (ba) it is one of several conditional forms, translated as "if" or "when".

No contractions occur with the izenkei. You can find more information on the use of the izenkei + ば (ba) construction here.

Izenkei conjugations

Group 2 conjugations		to eat		to see
Rentaikei		食べる taberu		見る miru
Izenkei		食べれ tabere		見れ mire

Group 4 conjugations		to write		to buy		to wait		to lend
Rentaikei		書く kaku		買う kau		待つ matsu		貸す kasu
Izenkei		書け kake		買え kae		待て mate		貸せ kase

Irregular verbs		to do		to come
Rentaikei		する suru		来る kuru
Izenkei		すれ sure		来れ kure

Verbal adjectives		to be large		to be new
Rentaikei		大きい ookii		新しい atarashii
Izenkei		大きけれ ookikere		新しけれ atarashikere

Verbal adjective		to be good (irregular)
Rentaikei		いい/良い ii / yoi
Izenkei		よけれ/良けれ yokere

All verbs have a regular izenkei conjugation.