第3部分：概括大意与完成句子(第23～30题，每题1分，共8分)
下面的短文后有2项测试任务：(1)第23～26题要求从所给的6个选项中为指定段落每段选择1个最佳标题；(2)第27～30题要求从所给的6个选项中为每个句子确定1个最佳选项。
23．Paragraph 2_______________
24．Paragraph 4_______________
25．Paragraph 5_______________
26．Paragraph 6_______________
27．Doctors envision that the nanomotor would travel through human bodies to____________．
28．Surface tension means the tendency of atoms or molecules to____________．
29．Nanoconveyors could be used to____________．
30．Applying a small electric current causes atoms to____________．
