Figures of speech from the description like a thin stalk of corn

In this unit we learned about arguments and rhetoric. in an argument we use ,not informal language

Then she heard his step on the stair away down on the first flight, and she turned white for just a moment. the phrase "she turned white for just a moment" is mainly used to show that della has very fair skin. is afraid of jim's reaction. is beginning to get an illness. had become extremely angry.

Can someone me answer this english question