Mrs.Peters stopped playing the piano when she began to work.She had lived in a very small flat,and there had been no room for a piano.But when she married,she had a new flat which was big enough for one.So she decided to get one and her husband agreed and helped her.She saved some money,and her parents gave her a generous amount of money for her birthday.Then she went to a shop and said,"l'll choose whichever piano does not cost too much and fits into my living room."
When she had paid for the piano,the shop assistant asked her if she would like him to get it tuned（调音）every few months.Mrs.Peters agreed.
A few months later she heard from the shop that a man was coming to tune the piano at ten that morning.Now she had not cleaned the house yet,so it was dusty and untidy.Mrs.Peters hated having even the least amount of dirt,and felt ashamed whenever strange people saw her house like that.So she had to hurry to clean everything carefully.It meant a lot of effort,and it made her hot and tired,but anyhow,by the time the man arrived,everything was finished.
She opened the door,and the man was standing with his big dog."Good morning,"the man said politely,"Will it disturb you if I bring my dog in,please? I' m blind,and he leads me wherever I go."
"It meant a lot of effort,and it made her hot and tired".Here"it" refers to____.（ ）
根据上下文可知，此句中“it”指前一句所做的事情，即clean everything carefully。
