解析：选C　细节理解题。根据第一段倒数第二句可知，如果父母在家里对家人大喊大叫或与人争吵，孩子也会这样做。

　　4．At school it's important for children to ________.

　　A．follow their teachers completely

　　B．stay away from ill­mannered students

　　C．avoid communication with others

　　D．get rid of their ill manners

　　解析：选B　推理判断题。根据第二段第四句可知，孩子与一些举止不良的学生为伴，他们也会变坏，所以对孩子来说远离这些学生很重要。

　　5．What does the passage mainly talk about?

　　A．How children choose their role models.

　　B．Who is the best role model for children.

　　C．How role models influence the children.

　　D．Why children learn from role models.

　　解析：选C　主旨大意题。综合全文可知，文章分别论述了家长、老师、同学和电视人物作为孩子的行为榜样，是怎样影响孩子的。

　　C

　　A new kind of surgical knife can tell cancerous from healthy tissue in seconds and may help improve tumor (肿瘤) removal in the operating room.

　　Known as the iKnife, the tool analyzes the vapour given off as surgeons use electrical current to cut away tissue, and it reports in real time whether the tissue is cancerous or not.

　　Tests in 91 human patients have shown the tool's diagnoses were extremely accurate, and may be reliable enough to begin widespread use in operating rooms.

　　The iKnife uses mass spectrometry (质谱法) to examine the surgical smoke given off by tissue, informing the surgeon in three seconds as to what it contains.

　　Other current techniques, which include sending removed tissue to a lab for analysis, are costly and frequently inadequate and take about 20－30 minutes.

　　"Remarkably, there are almost no technologies in routine clinical practice to assist the surgeon in improving the accuracy of cancer tissue clearance，" said the study.

　　For patients, this uncertainty can lead to repeat surgeries or worse, since returning to the operating table is not always an option for soft tissue tumors.

　　The iKnife can make current tumor diagnostics more accurate, and it has the potential to influence on­table decision­making and ultimately to improve oncological (肿瘤学的) outcomes.

In Britain alone, there are 300,000 new cases of cancer each year and 1.8 million surgical procedures performed in treatment.