在石质地面上追踪动物很困难。

It's difficult to ___track an animal over stony ground.

军方使用雷达卫星在云层中和夜间追踪目标。

The military use radar satellites to ___track targets through clouds and at night.

恐怖分子被追踪到阿姆斯特丹。

The terrorists were ___tracked to Amsterdam.