漏洞抢护原则是（）、（）、（）。
参考答案：前堵后导；抢早抢小；一气呵成
--What’s wrong with you?
---I have a _______.The doctor asked me not to eat anything today because I ate too much yesterday.
A．toothache
B．headache
C．sore back
D．stomachache
重复频率
