My teacher gave interesting assignments andmotivating the students.
很显然，这个
当我们重复使用一个短语或单词的时候，不仅会给人以词汇量过小的感觉，有时甚至也会造成误解，这对于托福口语分数是很有影响的。我们来看一个例子：
My teacher wrote the assignment on the chalkboard. The assignment was on thechalkboard until the teacher erased the assignment after we had all done the assignment.事实上这句话的观点会更加清晰，如果我们将重复的词替换为其他表达的话。我们再来看看改进后的表达：
My teacher wrote the assignment on the chalkboard. She erased the board after we had allcompleted the task.
其中 assignment 被替换为 task; teacher 变为了she; chalkboard 被改为了board. 不但句子显得更加生动活泼不刻板，信息量也比原来要多了。