下列句子中，没有语病的一项是

A．今天老师又在班会上表扬了自己，但是我觉得还需要继续努力。

B．中国不存在纯种汉族人与长期的大规模人种迁移也有关系，在很长的历史时期内，周边少数民族甚至周边国家都在不断与汉族融合

C．这一桩发生在普通家庭中的杀人悲剧在亲戚当中也有着不解和议论，要说小莉的妈妈不爱她家里人谁也不相信。

D．在这次民族联欢节中，举行了各种民族体育比赛，主要有赛马，摔跤，抢花炮，赛歌等，丰富多彩的比赛受到来宾的热烈欢迎。

Inside the computer, the operation system (of another software module called a data communication (71) )must decide which program will get control next. Each program remember, is associated (72) . a particular front -end port. If a program’s data have not yet reached its front - end buffer, there is no point giving that program control. Thus the data communication monitor sends its own (73) signal to the front -end devices next port is polled. Note that the (74) computer speed. The computer never has to wait for a terminal or a communication line. Instead, it is the expressive front - end processor that waits for the slower system (75) to respond.

（73）处填（）。

A．palling

B．pulling

C．polling

D．isolate