在数字通信系统中为提高通信系统有效性，可以采取的措施有（）
A、信源编译码
B、信道编译码
C、码元同步
D、群同步
参考答案：D
根据句意及汉语提示完成单词。
1. The football match______ (结束) at half past nine.
2. My school is next to my ______ (房子), so I often go to school on foot.
3. I have ______ (正餐；晚饭) with my family at home.
4. Class is over. Let's have a ______ (课间休息).
5. On Saturday we watch TV ______ (或者) play games.
胆道感染宜选用
A．四环素
B．青霉素G
C．庆大霉素
D．氯霉素
E．异烟肼
