图书馆禁止借阅色情刊物。

The library doesn't allow borrowing ___smut.

玉米因感染黑穗病而减产严重。

The corn crop suffered heavy losses due to ___smut infection.

他擦完汽车排气管后，袖子上沾满了煤灰。

His sleeves were stained with ___smut after wiping the car's exhaust pipe.