如果∠a=40°，那么∠a的余角等于______．
∵∠a=40°，
∴∠a的余角=90°-40°=50°．
故答案为：50°．
.
----I’m going downtown. ----Come on, _______.
A．I’ll give you a lift
B．You are welcome
C．Don’t do that
D．Come with me
怎样减少轴封损失？
