1. So this should immediately look like a problem because we know, in fact, that methane is tetravalent, and this is telling us it's only divalent.
显然这看起来是一个问题，因为我们知道实际上，甲烷是四价的，而这告诉我们它仅仅是二价的。
youdao
2. A tetravalent meningococcal meningitis vaccine (licensed in the United States) and a heptavalent vaccine protecting against meningitis A and C (to be licensed in 2007);
3. Conclusion the developed synthetic medium and purification procedure were feasible and provided an experimental basis for the preparation of tetravalent meningococcus polysaccharide vaccine.
4. Conclusion the developed synthetic medium and purification procedure were feasible and provided an experimental basis for the preparation of tetravalent meningococcus polysaccharide vaccine.
