解:原式=2.236+0.143﹣(4.375﹣0.75)
=2.236+0.143﹣3.625
=2.379﹣3.625
=﹣1.246
≈﹣1.25.
给婴幼儿接种脊髓灰质炎疫苗可预防脊髓灰质炎,下列关于该疫苗的说法正确的是( )