Choose the following statement which are non-firm offers. (请选出虚盘)
A、The quotation is subject to our final confirmation. 该报价以我方最终确认为准
B、Our offer is subject to goods being unsold. 该报价只限于未售货物。
C、Our offer is only for your reference. 该报价仅限参考。
D、Our offer is only valid for one month.