--- Must I finish my homework today?
--- No, you ______________. You ______________ finish it tomorrow.
A:can't; may
B:mustn't; must
C:needn't; may
D:mustn't; can
1mol甲苯中有6mol C﹣H共价键..(判断对错)
This big coat is . That is yours.
实验
药品
制取气体
量气管中的液体
①
Cu、稀HNO3
H2O
②
NaOH固体、浓氨水
NH3
③
Na2CO3固体、稀H2SO4
CO2
④
镁铝合金、NaOH溶液(足量)
H2
请回答下列问题:
cos60°=( ).