题目

淀粉、唾液淀粉酶和控制合成唾液淀粉酶的基因，它们的基本组成单位依次是（    ）     A．葡萄糖、葡萄糖和氨基酸   B．葡萄糖、氨基酸和脱氧核苷酸     C．麦芽糖、氨基酸和核糖核苷酸   D．葡萄糖、氨基酸和核糖核苷酸 答案：B —Why haven’t you asked her to come here? —She _______ an important experiment when I found her and she _____ it. A．had done ; didn’t finish B．was doing ; hasn’t finished C．did ; wouldn’t finish D．did; hadn’t finished