双基限时练(十) unit 5 grammar 1 ⅰ.单句语法填空(不多于3个单词) 1．we were about to leave ________ he came in. 答案 when 2．we always sing ________ we walk. 答案 as 3．it will be four years ________ they come back. 答案 before 4．i have been in beijing ________ you left. 答案 since
