填 have changed
用现在完成时强调对现在的结果‘ 电话已改变了我们的交流方式’
加油!不明白再问!Shoping on the Internet isn't always safe变为同义句___ __ ___ ___shop on the Internet.(It isn't safe to ) shop on the Internet . 注；it 's +adj.+to do sth 固定用法‘ 做……是……’