1 and 2 are examples of present subjunctive, used more in those days than nowadays 3 - 'Be' cannot be used there; it is a Conditional I, which uses indicative verb forms. 4 - as 1 and 2, or perhaps just a frozen poetic form: 'Home, Sweet Home' was written in 1822. 5 - as 1 and 2, an older form; we'd use 'is' now.
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