关于温度、内能和热量,下列说法正确的是( )
A:物体温度降低时内能减少
B:0℃的冰变成0℃的水,温度不变,内能不变
C:温度相同的两个物体间不能发生热传递
D:任何物体都具有内能,通过摩擦可增大冰块的内能
以坐标原点O为圆心,作半径为2的圆,若直线y=﹣x+b与⊙O相交,则b的取值范围是( )
(____) He is making a birthday card.
(____) He's in his room.
(____) When is Jack's birthday?
(____) Where's Jim?
(____) Who is he making it for?
(____) What is he doing?
(____) Tomorrow.
(____) He is making it for his friend,Jack.
已知:
①LiBH4可将醛、酮、酯类还原成醇,但不能还原羧酸、羧酸盐、碳碳双键;LiBH4遇酸易分解.
②RCH2COOR′ →催化剂CH3I RCH(CH3)COOR′
RCOR′ →THFLiBH4 RCH(OH)R′R﹣COOR →THFLiBH4 RCH2OH+R′OH
请回答下列问题: