题目

 One day, I was walking with my daughter, and we saw a man picking bottles out of garbage cans (垃圾箱). He did not ask us 41  spare change, like others had before him. My 10-year-old daughter asked 42  he was doing that, as he appeared to be unclean and possibly 43. I told her he had his dignity (尊严), and was doing what he could to help 44 . My daughter had a 2-dollar 45 I had given her, and she told me she 46 to give her money to this man 47she thought he needed it more than she 48. I agreed. We are on welfare (领取福利救济), 49 we have a place to live, and food to e如图是设想的一条生物合成途径的示意图。若将因基因突变而缺乏某种酶的微生物置于含物质X的培养基中生长，发现该微生物内有大量的M和L，但没有Z，试问基因突变影响到哪种酶的合成（  ） A.E酶       B.B酶        C.C酶       D.A酶和D酶