葡萄糖效应
参考答案：
葡萄糖的分解代谢产物阻遏了分解利用乳糖等其他糖类的有关酶的合成这种阻遏~
— Have you known Mrs. Jackson for a long time?
— Yes, since she _____ the music club. [ ]
A. has joined
B. joins
C. had joined
D. joined
