  Simultaneous multiwavelength observations were recently performed for three
black hole candidates --- SWIFT J1753.5-0127, GRO J1655-40 and XTE J1720-318.
In this paper we test the accretion-jet model originally proposed to XTE
J1118+480 by investigating the hard state of these three sources using this
model. The accretion flow in the model is composed of an inner hot accretion
flow and an outer truncated thin disk. We find that the model satisfactorily
explains the spectrum ranging from radio to X-rays, with the radio and X-ray
spectra dominated by the synchrotron and thermal Comptonization emissions in
the jet and the hot accretion flow respectively, while the infrared and optical
being the sum of the emissions from the jet, hot accretion flow, and the
truncated thin disk. Similar to the case of XTE J1118+480, the model can also
explain, although only qualitatively in some cases, the observed timing
features including QPO, and positive and negative time lags between the optical
and X-ray emissions detected in SWIFT J1753.5-0127. The origin of the ejection
events detected in XTE J1720-318 is also briefly discussed.
