The expression of warning against thedanger of falling down. Thanks for corrections.

“I guess we need a moving staircase to clean the outside this porthole window,” she remarked.
“Yes, mother,” replied I.
“Let's bring it here under the porthole,” she offered.
“Let's not, mother,” I expressed my anxiety.
“Don't worry, I'll be okay,” she laughed and patted my head.
“Let me do it then, I am smaller than you,” I offered.
“Thank you my little man, but you are small enough not to control your movement,” she pointed out.
“Mother, be careful,” I expressed my concern about the state of the moving staircase.
“I know son, just hold it firm and don't let it move,” she admitted and pointed cautiously.
We went to the stair head grabbed the moving staircase and brought it in the kitchen under the porthole. Her feet hardly touched the stairs as she gingerly crept up through the staircase. Coming to the top stair, with a wet cloth at hand, she paused a second to take a breath, and then, she opened the window of the porthole, took her head out through the window and stretched her hand out to try to reach the outside of the window. She tried hard, but she couldn't reach the whole glass surface. She gave up putting any more effort on cleaning. She descended the narrow stairs, at the bottom of the staircase she stepped onto the kitchen floor.
“I cannot do more than this,” said my mother in frustration.
She washed and cleaned every corner of the house. Since her hand could not reach the outside of the porthole my mother was not able to clean the outside of it. We went downstairs leaving the moving staircase under the porthole.