What’S the main idea of the passage7
A．Laser light treatment of heart disease should take the place of the traditional operatlon．
B．Laser light treatment has been proved better and more effective than the traditional operation．
C．More advanced technology should be encouraged to try on．
D．Laser light treatment of heart disease still needs’more research．
正确答案：D
通读全文特别是最后一段后半部分可知正确答案应是D项
