No free plastic bag in the supermarket helps to _____ white pollution.

__________ is known to all, China will he an ________ and powerful country in 20 or 30 years’ time.

(2013山东济宁)The earthquake in Ya’an left________people homeless．

Have you been to the Great Wall?— Perhaps not in my memory. _________, it might have been during my early childhood.[ ]

I think it ______ that she should be knowledgeable about computers for her present job.