Children vary considerably in the rate at which they learn these lessons.

孩子们学习这些课的速度差别相当大。

Stellar spectra vary considerably.

恒星的光谱有相当大差异。

Fridges also vary considerably in efficiency.

不同冰箱的效率差别很大。

The actual costs of an OER project vary considerably.

OER项目的实际代价变化相当大。

Though obviously that time can vary considerably.

显然，这个时间变化幅度很大。