been > [are, have]
2 They in that garden planted be again; 3 And grow afresh, as they had never seen
as > [as though]
4 Fleshly corruption, nor mortal pain. 5 Some thousand years so do they there remain;
so > thus
6 And then of him are clad with other hue,
of > by hue > appearance, form
7 Or sent into the changeful world again,
Or > (Possibly a misprint for "And"; for a summary of other explanations, see Hamilton (1980))
8 Till thither they return, where first they grew: 9 So like a wheel around they run from old to new.