Module 4 Great Inventions Unit 3 Language in use Language practice Paper and printing have been used for ages. The battery hasnt been changed for a couple of months. Has it been published yet? Information can be kept on CD-ROMs. Books could only be produced one at a time. Can books be replaced by computers? 现在完成时的被动语态： have/has（ not） been +过去分词 情态动词的被动语态： 情态动词（ not） + be + 过去分词 一般现在时 am is are +动词的过去分词 一般过去时 was were +动词的过去分词 一般将来时 will be be going to be +动词的过去分词 情态动词 aux. v. (must can could may
