Copyright © 2010 Xiangdong Xie et al. This is an open access article distributed under the
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A class of cubic systems with two invariant straight lines is studied. It is obtained that the focal quantities of are, ; if , then ; if , then ; if , then is a center, and it has been proved that the above mentioned cubic system has at most one limit cycle surrounding weak focal . This paper also aims to solve the remaining issues in the work of Zheng and Xie (2009).