铁路承运人的免责事项不包括（）。 A.不可抗力 B.货物本身的自然属性或者合理损耗

(l)a g O₂中含N个氧原子，则阿伏加德罗常数为___；

(2)在标准状况下，V LH₂中含有N个氢分子，则阿伏加德罗常数为____；

(3)m g H₂和O₂的混合气体中含N₁个氢分子和N₂个氧分子，则阿伏加德罗常数为____。

A client in her 7th month of pregnancy has been complaining of back pain and wants to know what can be done to relieve it. Which of the following responses by the nurse is most effective ？（）

A．"You need to lie down more during the day to get off your feet. "

B．"Avoid lifting heavy loads, and try using the pelvic tilt exercise. "

C．"Have others pick things up for you so you don't have to bend over so much. "

D．"Your back pain will go away after the baby is born. "

题干: 远期交易收取多少保证金由交易双方商定，甚至双方可以商定不收保证金。

简述胸腔积液的体征。

企业关心的是赢利，员工的利益要服从于企业的这一目标