怎样取得本月的第一天以及最后一天。方法有以下几种：

1.     DateTime FirstDay = new DateTime(DateTime.Now.Year,DateTime.Now.Month,1);       

        DateTime LastDay = new DateTime(DateTime.Now.AddMonths(1).Year,DateTime.Now.AddMonths(1).Month,1).AddDays(-1);

2.　  DateTime FirstDay = DateTime.Now.AddDays(-DateTime.Now.Day+1);
        DateTime LastDay = DateTime.Now.AddMonths(1).AddDays(-DateTime.Now.AddMonths(1).Day);