模 块 3 unit 7 the sea 一、语法专项训练用所给单词的正确形式完成下列句子。 1．the problem is difficult__________(solve)． 2．__________(work) in beijing for ten years，he returned to his hometown to set up his own business. 3．the bridge，__________(complete) last october，will be open to traffic next month. 4．with the problem__________(solve)，he continued his research work.
