Ⅰ.单词拼写
1．I had to change my ______(态度) about their ability and potential.
2．Americans use more than 100______ (十亿) thin film plastic bags every year.
3．When writing papers, we have to ______ (查阅) to a lot of reference books concerned.
4．It was his first visit to his ______(出生地的) country since 1948.
【答案】1.attitude 2.billion 3.refer 4.native
