straight multiple

例句：

1. 1.The straight multiple of 5 is 25.
   5的直线倍数是25。
2. 2. The product of two numbers is their direct multiple.
   两个数的乘积是它们的直接倍数。
3. 3. When the temperature rises, the water expands and its volume increases, making it a direct multiple of its initial volume.
   当温度升高时，水膨胀并增加体积，使其成为其初始体积的直接倍数。