That means teachers don't track test scores or grades.

意思是教师不会跟踪学生考试成绩或等级。

The company has a test track in the state of Nevada near Las Vegas.

该公司在内华达州拉斯维加斯附近有一条测试跑道。

And after building that system, we created a test track in the desert outside of Las Vegas.

在构建该系统之后，我们在拉斯维加斯以外的沙漠中创建了一条测试轨道。