金刚石钻进用的钻具目前分为单管钻具、普通双管钻具和（）。
A、绳索取心用双管钻具
B、双管钻具
C、多管钻具
D、专用单管钻具
参考答案：A
与细菌致病作用有关的主要因素有哪些?
根据句意及汉语提示完成句子
l. We all think_________ (友谊) should be the most important in the world.
2. It's our ________(职责) to save all the people's lives here.
3. Being a _______(士兵).is Stephen's dream.
4. China's _________(发展)makes people around the world feel surprised.
5. His idea often (影响)his decisions.
