China has a population of a thousand million.我想请问一下这句population 前为什么还要加个a

China has a large population. China has a long____(历史). China has a colorful ______(文化）. china has a very long h__. 请教2道英语选择题（关于定冠词的）1.____ doctors and ___ nurses should care for their patients.a..The,the b./,/ c.The ,/ d./,the2.Long long ago,there were very ____people in this place,but now it has become a town with a large populati Sandy has a map of china怎么用what提问? China has a long history的同意句 China has changed a lot in the past twenty years 英语翻译China has a more population than America Sanys has a map of China.(用WHAT提问） china has a rich and colorful cultural history ad masks China has changed a lot in the _______(twenty) chentury Our class has a mop of China改为同义句 China has become a member of the world community 大明 has got a stamp from china.变否定句 China has a p of about 1.3 billion China has developed a lot already什么意思 China has developed a lot already什么意思