每天交接班时（）都要按使用和保管分工对执勤器材装备进行每日擦拭保养一次。 A.驾驶员

主照明系统应能提供充分的照明，由（）供电。

在直角三角形中，一个锐角的对边与邻边的比，叫做这个锐角的（　　）

A．正切三角函数

B．余切三角函数

C．正弦三角函数

D．余弦三角函数

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One day, a poor boy was selling goods from door to door to pay for his tuition fees (学费). He was hungry. He d___1____ he would ask for a meal at the next house. However, he lost heart w___2____ a lovely young woman opened the door. He asked for a drink of water and the woman agreed. She thought he looked hungry, so she b___3____ him a large glass of milk. He drank it slowly, and then asked, “How much do I owe (欠) you ?” “You owe me nothing, ” she r___4___. “Mother has taught us never to accept pay for a kindness.” He said, “Then I thank you from my heart.”

Years later, that young woman become seriously i__5___.The local doctors all f__6___ to cure her. They finally sent her to the big city, where they called in specialists (专家) to study her rare disease. Dr. Howard, who o__7__ got a large glass of milk and a meal from the young woman, was called in for the treatment. He went down the hall of the hospital to her room when he heard the name of the town she came from. D__8____ in his doctor’s uniform, he went in to see her. He recognized (认出) her quickly. He made up his mind to do his best to save her life and pay special a__9_____ to the case. After a long struggle, the battle (战役) was won. The woman n__10____ these words when she paid the pill: “ Paid in full with one glass of milk… Dr. Howard Kelly..”

欲使任何一种不饱和溶液转变为饱和溶液，下列措施肯定不可行的是（　　）

A．改变温度

B．蒸发溶剂

C．倒出溶液

D．加入溶质

调节阀阀内件材料的选择依据与被调介质的（）无关。

A、黏度

B、温度

C、腐蚀性

D、磨损性