治疗伤寒的首选抗生素是
A．青霉素B．氯霉素C．四环素D．氨苄青霉素E．庆大霉素
参考答案：B
It is ten years _____ I lived in Nanjing, so I know ____ about what it is like today.
A．since; nothing
B．that; everything
C．before; something
D．since; anything
图示外伸梁，弯曲变形后，A、C两截面转角的关系是（）。
A．|θA|＞|θc|
B．|θA|＝|θC|
C．|θA|＜|θC|
D．不能确定
