钢筋必须按不同（）分批验收、分别堆存，不得混杂，且应设立识别标志。
A.钢种
B.等级
C.牌号
D.规格及生产厂家
参考答案：A, B, C, D
监事会和连续90日以上单独或者合计持有公司20%以上股份的股东拥有补充召集权和补充主持权。( )
Many Chinese students think science subjects are _______ foreign languages.
A．more difficult as
B．less difficult than
C．much difficult than
D．so difficult as
