题目

据估计，目前我国每年返回餐桌的地沟油有200万～300万吨．地沟油，又叫“黑心油”，是一种质量极差、极不卫生的非食用油，它含有毒素，其中黄曲霉毒素M1（C17H12O7）是一种高致癌物质．下列有黄曲霉毒素M1的说法中正确的是A．黄曲霉毒素M1中各元素的质量比为17：12：7 B．每个黄曲霉毒素M1分子中质子数为170 C．黄曲霉毒素M1属于有机高分子化合物 D． ．The first half of the eighteenth century _____ the rise of quite a number of new writers, although most of them _____ hardly _____ to the general public today.A. sees; ×; know             B. saw; are; knownB. has seen; have; known      D. had seen; have; been known