The best replacement for modal verbs is auxiliary verbs.

The best alternatives to modal verbs are rated as following:
★★★★★  auxiliary verbs

Your alternative for modal verbs is not listed? Suggest!
Speaking about modal verbs, one probably shouldn't forget about passives.

Other search terms related to modal verbs and their ratings are:
★★★★★ passives
★★★ perfect infinitive
★★ passive german
★ conditional
You have in mind a companion for modal verbs and it is not yet here? Propose!



Google Trends

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modal verbs
auxiliary verbs