本合同由A公司（以下称之为“卖方”）与B公司（以下称之为“买方”）共同订立，鉴于卖方愿意依据下列规定的条款售卖下述商品，兹特立约为据，并由订约双方协议如下。This contract is made by and between A Co. (______ called “the seller”) and B Co. (______   called “the buyer”), _______ the seller is willing to sell the buyer the commodities listed hereunder on the terms and conditions stipulated below. Now these presents witness that it is ________ agreed between the parties hereto as follows. 
A、hereof, hereof, whereas, therefore
B、thereafter, thereafter, whereby, thereinafter
C、whereof, whereof, whereby, hereby
D、hereinafter, hereinafter, whereas, hereby