1. 昨天这个时候他正在帮老师发书。
    He was helping the teacher ________ ________ the books at this time yesterday.
2. 这个游戏的目的是周游世界了解各地的历史。
    The goal of the game is to ________ ________ the world to learn the history of each place.
3. 她边等车边看书。
    He was reading ________ he was waiting for a bus.
4. 老人独自住在林子里,但他并不感到孤独。 
   The old man lives ________ in the village, but he does not ________.
5. 我去过北京两次.我是在2001和2004年去那里的。
    I have ________ to Beijing twice. I ________ there in 2001 and 2004.