烷烃和烯烃一样,不仅有构造异构体,还有立体异构体存在。
参考答案:错
解析:烷烃没有立体构造异构体。
有关支气管肺炎与婴幼儿活动性肺结核,下列哪项最有鉴别意义()
A.发热高低
B.咳嗽程度
C.有无气促
D.肺部固定湿啰音
E.乏力、食欲缺乏
请完善程序(程序文件名:Java_3.java)并进行调试。请在下画线处填入正确内容,然后删除下画线。请勿删除注释行和其他已有的语句内容。 [题目要求] 统计一个英文文本字符串包含的英文元音字母的个数,使程序的运行结果如下: The text contained vowels:88 源程序:public class Java_3 public static void main(String[] args) String text = " Beijing, the Capital City, is the political, "+ "cultural and diplomatic centre of China. It has"+ "become a modern international cosmopolitan city"+ " with more than 11 million people. The Capital"+ " International Airport, 23.5 km from the city centre,"+ "is China’s largest and most advanced airport. " ; int vowels =0; int (1) = text.length(); for(int i = 0;i<textLength; i++) char ch=Character.toLowerCase( text. (2) ); if(ch==’a’||ch==’e’||ch==’i’||ch==’o’||ch==’u’) (3) ; System.out.println( "The text contained vowels:" + vowels +"\n");