Without referring to the chapter, draw the chair conformations of (a) -D-mannopyranose (the C2 epimer of glucose)

Without referring to the chapter, draw the chair conformations of
(a) β-D-mannopyranose (the C2 epimer of glucose)
(b) α-D-allopyranose (the C3 epimer of glucose)
(c) β-D-galactopyranose (the C4 epimer of glucose)
(d) N-acetylglucosamine, glucose with the C2 oxygen atom replaced by an acetylated amino group