A:____.
B:Good evening.
A:____?
B:I have dinner at half past six.
A:____ ?
B:No, I don't eat rice.____?
A:I have dinner at seven and I eat rice.
B:At home?
A:Yes.____?
B:I have dinner at home too.
∵AO⊥CO,
∴∠AOC=____(____).
又∵∠COD=40°(已知),
∴∠AOD=____.
∵∠BOC=∠AOD=50°(已知),
∴∠BOD=____,
∴____⊥____(____).