⑴How many seasons are there in a year?____   A. Four

⑵What about some milk?____             B. She's in the kitchen.

⑶What would you like?____                  C. They're on the sofa.

⑷Where are my warm clothes?____           D. Sounds good.

⑸I can't find Mum.____                      E. I'd like a hamburger.

如图，△ABC内接于⊙O，OD⊥BC于D，∠A =50^°，则∠OCD的度数是（  ）

关于电流做功过程中的能量转化，下列说法中错误的是（　　）