General Motors Corp said on Tuesday it reached a tentative deal to sell its Hummer brand to a privately held Chinese company, part of an effort to drop four unprofitable vehicle lines and leave bankruptcy as a leaner company.     通用汽车继周一宣布破产后，周二就把旗下著名军用越野品牌“悍马”出售给*私营企业四川腾中重工业机械有限公司。