HSK 5
Zhè yī dìqū de dàxióngmāo zhǒngqún zhèngzài zhújiàn huīfù.
The giant panda population in this region is gradually recovering.
HSK 6
Kēxuéjiā yánjiū zhǒngqún de shùliàng biànhuà yǐ liǎojiě shēngtài xìtǒng.
Scientists study population changes to understand ecosystems.
HSK 7-9
Guòdù bǔliè dǎozhì gāi yúlèi zhǒngqún jíjù jiǎnshǎo.
Overhunting has caused a sharp decline in the fish population.
