Sing. I might, thou mightst, he might; Plur. We might, you might, they might.
CAN.
PRESENT TENSE; AND SIGN OF THE POTENTIAL PRESENT.
Sing. I can, thou canst, he can; Plur. We can, you can, they can.
IMPERFECT TENSE; AND SIGN OF THE POTENTIAL IMPERFECT.
Sing. I could, thou couldst, he could; Plur. We could, you could, they could.
MUST.
PRESENT TENSE; AND SIGN OF THE POTENTIAL PRESENT.
Sing. I must, thou must, he must; Plur. We must, you must, they must.
If must is ever used in the sense of the Imperfect tense, or Preterit, the form is the same as that of the Present: this word is entirely invariable.