linear whole body scanner

例句：

1. 1. The line of the road is straightas an arrow.
   这条路线直得像箭一样。
2. 2. The linear growth of the population hasbeen a concern for policymakers.
   人口的直线增长一直是政策制定者关注的问题。
3. 3.The linear equation can be solved by usingthe method of substitution.
   这个线性方程可以通过替换法来求解。