A:a基因产生的原因可能是其亲代产生配子时发生了基因突变
B:该细胞一定发生了染色体变异,一定没有发生基因自由组合
C:该细胞产生的各项变异均可在光学显微镜下直接进行观察
D:该细胞的变异均为可遗传变异,都可通过有性生殖传给后代
根据句子意思,用括号中所给汉语提示或英语单词的适当形式填空。在答题卡标有题号的横线上,写出空缺处所填单词的正确形式。⑴The workers told the police their ____ (老板) name.⑵In his ____ , he passed away peacefully in his dream(九十).⑶The kids couldn't stop____ when they saw their favourite Disney characters (尖叫).⑷The foreign visitors____ come from North America (大部分).⑸The door is wide enough for three people to walk____ at the same time (通过).⑹I wonder how much a panda usually ____ (weight) when it is born.⑺Tom is such a ____ boy that he always tells a lie when he makes a mistake (honest).⑻The neighbours lost ____ (they) in the strange city.⑼The plan they are talking about ____ (need) improving.⑽He had his computer ____ (fix) shortly after it broke down.
如图,△ABC内接于⊙O,半径为5,BC=6,CD⊥AB于D点,则tan∠ACD的值为____.
阅读如图所示的程序框图,则输出的S=( )