题目

下列有关减数分裂的叙述，正确的是（ ） A．是一种特殊的无丝分裂 B．在形成有性生殖细胞的过程中发生 C．染色体复制2次，细胞分裂2次 D．分裂的结果必定是形成4个生殖细胞 答案：解：A、减数分裂是一种特殊方式的有丝分裂，A错误； B、减数分裂在形成有性生殖细胞的过程中发生，B正确； C、减数分裂过程中染色体复制1次，细胞分裂2次，C错误； D、一个精原细胞经过减数分裂能够产生4个精子，但是一个卵原细胞经过减数分裂只能产生一个卵细胞，D错误． 故选：B．缺词填空Computers are useful machines. Today more and more families o___【1】__ computers. Parents buy computers for their children because they hope computers can h__【2】___ them improve (提高) their studies at school. But many of the children u___【3】___ them to play games, watch films or listen to music. So some teachers and parents t___【4】___ that computers cannot help children to study but make them fall b___【5】__. So some parents p___【6】___ computers in the drawers (抽屉).In some other countries, even the scientists (科学家) h__【7】___ computers. They say computers let millions of people lose their j___【8】__ or bring them a lot of trouble.Will computers r___【9】___ bring trouble to people or bring people happiness? One must decide (决定）h___【10】___ to use computers.