英语语法分析

Tetracycline in their food probably explains the low incidence of typhus among ancient Nubians.

它们的食物中含有四环素，这可能是古努比亚人斑疹伤寒发病率低的原因。

The strains are sensitive to tetracycline, doxycycline and ciprofloxacin.

该菌对四环素、强力霉素、环丙沙星敏感。

For those who are allergic to penicillin, tetracycline, erythromycin and doxycycline could be used.

对青霉素过敏者可使用四环素、红霉素和强力霉素。