题目

Music to My Ears Robby was 10 for his first piano lesson in my class. Much as he tried, he __41__ even the basic rhythm. However, he dutifully reviewed the pieces that I required. Over the months he tried and tried while I __42__ and encouraged him. At the end of each lesson he'd always say, My mom's going to hear me play some day. __43__ it seemed hopeless. I only knew his mother from a __44__as she waited in her aged car to pick him up. Then one day Robby stopped coming. I was secretly __45__ that he stopped because of his lack of ability.     Weeks later I informed the student嫩肉粉可将肌肉组织部分水解，使肉类食品口感松软、嫩而不韧。嫩肉粉中使肉质变嫩的主要成分是A. 淀粉酶 B. DNA酶 C. 蛋白酶 D. 脂肪酶