C186 How do you want to verify

"Doctor Zhan? Is this safe? " a doctor asked.

Zhan Xiaolou smiled.

"Absolutely safe, I'm sure."

"But how can the pox be safe? Doctor Zhan, have you ever verified it?" Dr. Feng said as he took a few steps forward.

That's right, have you verified it?

Everyone had the same question in their hearts.

Zhan Xiaolou picked up the copper pipe again, "Arsenic