题干
There some flowers in the garden.
A：were used to be
B：used to be.
C：used to have
答案(点此获取答案解析）
B
There some flowers in the garden.
A：were used to be
B：used to be.
C：used to have
标记的胸腺嘧啶脱氧核苷培养基中完成一个细胞周期，然后在不含放射性标记的培养基中继续分裂至中期，其染色体的放射性标记分布情况是