国家邮政局调查显示,电子商务已成为我国快递业发展的巨大推动力,全国快递业1/3业务量由电子商务带动完成。仅去年中国电子商务带动的包裹量就超过5亿件,电子商务和快递物流已经越来越成为人们生活中不可或缺的部分。对此,下列说法正确的( )①电子商务和快递物流之间存在着互为替代关系②电子商务和快递物流之间存在着互补关系③电子商务和快递物流的发展有助于推动我国产业结构的调整④电子商务和快递物流的发展表明我国居民恩格尔系数不断提高
I don’t think I am __________; it is said that _________ is the mother of success.
--- I’m afraid I can’t return the book to you before Friday. ---_______.
They are so busy that they have no time to do any sports, ______they need to do so.
I don't know _______.
Hurry up! The train ______. You know it ______ at 8:30 am.