In the last test, students had to copy a complex drawing onto a

In the last test, students had to copy a complex drawing onto a ______of paper, and then sketch the drawing from memory.
A、seam
B、sheets
C、layer
D、sheet
【正确答案】：D
【题目解析】：考查Unit nouns（单位名词）。固定搭配a sheet of，一张，一片。