英语语法分析

Erythema migrans appears at the bite site after three days to a month.

游走性红斑于3日至一个月后出现在被叮咬处。

Objective: To explore the possibility of immune prevention of larva migrans of Toxocara Canis.

目的：探索犬弓首线虫幼虫移行症免疫预防的可能性。