A:正反应放热,L是固体
B:正反应放热,L是气体
C:正反应吸热,L是气体
D:正反应放热,L是固体或气体
——Would you like tea or coffee?——________ ,thanks. It's hard for me to fall asleep at night after drinking them.
My daughter usually gets up at 6: 00 the morning, but Sunday morning she gels up at 8: 00.
下列有关碳循环的说法错误的是( )
下列各项,属于生物的是( )
如图,AB是⊙O的直径,⊙O的半径3cm,弦CD⊥AB于E,∠CDB=30°,则弦CD的长为( )