Using the 13.7m telescope of the Purple Mountain Observatory (PMO),a survey of the J = 1 - 0 lines of CO and its isotopes was carried out on 98 methanol maser sources in January 2008.Eighty-five sources have infrared counterparts within one arcmin.In the survey,except for 43 sources showing complex or multiple-peak profiles,almost all the 13CO line profiles of the other 55 sources have large line widths of 4.5km s-1 on average and are usually asymmetric.Fifty corresponding Infrared Astronomical Satellite (IRAS) sources of these 55 sources have Lbol larger than 103 L ,which can be identified as possible high-mass young stellar sources.Statistics show that the 13CO line widths correlate with the bolometric luminosity of the associated IRAS sources.Here,we also report the mapping results of two sources: IRAS 06117+1350 and IRAS 07299–1651.Two cores were found in IRAS 06117+1350 and one core was detected in IRAS 07299–1651.The northwest core in IRAS 06117+1350 and the core in IRAS 07299–1651 can be identified as precursors of UC HII regions or high-mass protostellar objects (HMPOs).The southeast core of IRAS 06117+1350 has no infrared counterpart,seeming to be at a younger stage than the pre-UC HII phase.
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