The second within-subject factor is difficulty, included three levels, easy, medium and difficult.

第二个因素是被试内变量，即阅读材料的难度，分为容易、中等、难三个水平。

youdao

This model included three levels: the global self worth, general self worth and special self worth.

该模型包括总体自我价值感、一般自我价值感和特殊自我价值感三个层次；

youdao

A high level energy group was added into this repeated experiment. The experiment included three groups i. e. high, medium and low energy levels.

本重复试验增加一个高能组，共设高、中、低三个能量水平组。

youdao

The arena design included over 175 suites on three different levels, and the lower level suites (sixteen rows from the floor) were a first in sports facilities design.

FORBES: Tom Gores Puts His Stamp On The Detroit Pistons With Arena Renovations