知識網內:But she could only picture her husband be with mistress. 本句picture為動詞,be動詞又何解?謝謝?

But she could only picture her husband sleeping with a mistress.

could is used in indirect speech in place of "can" if the main verb is past tense to express conditions, express occasional occurrence and express inclination. be is separated from could be meaning It can be(=sometimes it is)very sexy,jealous feeling with mistress=to be--an omission of to in (Q&A). Re:-Chen's The Heart of Grammar ,be=to be, as suggested , recommended by you---kuangkwo20.