2 sentences

1. 这里的河水需要定期采样。

   zhè​lǐ de hé​shuǐ xū​yào dìng​qī cǎi​yàng.

   The river water here needs to be sampled regularly.

   Source: Dong Chinese Dictionary

2. 采样方法不当会导致实验结果产生偏差。

   cǎi​yàng fāng​fǎ bù​dàng huì dǎo​zhì shí​yàn jié​guǒ chǎn​shēng piān​chā.

   Improper sampling methods can lead to deviations in experimental results.

   Source: Dong Chinese Dictionary