聚丙烯的立体异构包括全同（）、间同（）和无规立构。

.选词填空：根据所给词的适当形式填空10%

problem,  means,  serious,  be ,  food ,  well,  large,  population,   policies,   reached

Every minute about 261 babies  小题1:born in the world. That 小题2:people have to find  小题3:for about  375,840  newborn  babies every day. The world’s小题4:is growing faster and faster. It has become one of the greatest  小题5:today.
China has the  小题6:population in the world. There are about 1.3 billion people in China. It has  小题7:one fifth of the world’s population. China has  carried  out some     小题8:to control the population, and these policies have worked  小题9:. But China still faces a    小题10:population problem.