A ≤20cfu/m<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20221202/13375519_0.gif"> B
≤50cfu/m<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20221202/13375519_0_1.gif"> C
≤100cfu/m<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20221202/13375519_0_2.gif"> D
≤200cfu/m<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20221202/13375519_0_3.gif"> E
≤500cfu/m<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20221202/13375519_0_4.gif">