问题
完形填空
同义句改写
小题1:To plant trees every year is necessary for us.
______________for us to plant trees every year.
小题2:Paul left Canada two days ago.
Paul __________________Canada since two days ago.
答案
小题1:It is necessary
小题2:has been away from
小题1:考查固定句型。不定式可以作主语，it is necessary to do sth做某事很有必要，故填It is necessary。
小题2:考查时态。ago与过去时连用，since+含有过去时的句子，与现在完成时连用。leave是短暂动词，不能与一段时间连用，应该转换为be away，故填has been away from。