Q2. What is the meaning of passive verbs?
Various transitive verbs with causative, inchoative, or perception meanings take subjectless bare passive complements (that is, in effect, past-participial VPs).
Q3. What is the reason why English grammars fail to describe the passive adequately?
The failure of English grammars to describe the passive adequately is partly due to a centuries-old tradition of talking about English grammar as if English were typologically similar to Latin, the international language of higher learning at the time when grammatical study of English began.