¹¹B-NMR is an excellent spectroscopic tool for inferring the structures of boron compounds. With ¹¹B–¹¹B coupling ignored, it is possible to determine the number of attached H atoms by the multiplicity of a resonance: BH gives a doublet, BH₂ a triplet, and BH₃ a quartet. B atoms on the closed side of nido and arachno clusters are generally more shielded than those on the open face. Assuming no B–B or B–H–B coupling, predict the general pattern of the ¹¹B-NMR spectra of 

(a) BH₃CO

(b) [B₁₂H₁₂]²⁻.