while in some developing countries.为啥用while呀,咋看咋多余

while in some developing countries.为啥用while呀,咋看咋多余 mean?Some countries are rich while others are poor. 在句子“People in western countries celebrate Christmas,while in some developing countries the population is still i____此题 The population in developing countries is ()than() while(! 英文句子纠错Some countries have single-sex education models,while 翻译：some thing take a while to sink in. While __________ in London,the young engineer picked up some 英语翻译Some genes change rapidly in evolution while others have once in a while c语言 用二分法球绝对值绝对误差不超过0.001while(fabs(m-n)>0.001),为啥是大于啊,while内