急弯弯管秘回弯头弯管有和区别?
参考答案:
急弯弯管与回弯头相比,减少了漏点,减沙了散热损失,压降减小。但无法进行机械清焦,无法检查炉管内的结焦或清焦情况。
血友病指()
A.APTT正常、PT正常、BT延长、PLT正常
B.APTT正常、PT正常、BT延长、PLT减少
C.APTT延长、PT正常、BT正常、PLT正常
D.APTT正常、PT延长、BT延长、PLT正常
E.APTT延长、PT延长、BT延长、PLT正常
His family ____ a big one. Now the family ____ watching TV.
A.is, are
B.are, is
C.is, is
D.are, are