这些狗非常聪明，能学会很多指令。

These ___dogs are very smart and can learn many commands.

侦探紧盯着嫌疑人，不放过任何线索。

The detective ___tails the suspect, following every clue closely.

这款新游戏太烂了，根本不值得买。

This new game is such a ___dog - it's not worth buying at all.

这双新鞋磨得我脚疼。

These new shoes are killing my ___feet.