Modal verbs are easy to spot because there are so few of them. In addition to must, shall, will, should, would, can, could, may and might, we can add ought to and have to. If we are told that we 'must ...

Much research has focused on nonnative speaker (NNS) use of modal verbs of obligation and necessity, indicating that NNSs may have difficulty with these modals and use them in different contexts from ...