1. _______________ （隨著工商業(yè)的發(fā)展）,the number of trees in many big cities has dramatically reduced.

　　 2. Travel can widen our knowledge, _____________ （擴(kuò)大我們的眼界）,and make one open-minded as well.

　　 3. Cars are responsible for most of the smog in cities, _______________ （這已經(jīng)對(duì)環(huán)境造成了嚴(yán)重的污染）.

　　 4.Modernization will be entirely possible in the first half of the 21st century, as long as we ________________（堅(jiān)持認(rèn)為）that economic development is the center of all our work.

　 　5. He was convinced on the basis of ____________（當(dāng)時(shí)已出現(xiàn)的情況）that there would be a long and difficult struggle.

來源:可可英語 http://www.ccdyzl.cn/cet6/200905/71143.shtml