Many states in America have passed laws that say children cannot be enrolled in schools or day care unless they have been ______ against tetanus, diphtheria, measles, mumps and whopping cough.
考查动词辨析。A项diagnose表示“诊断,断定”,B项concur表示“同意,一致,互助”,C项immunize表示“赋予免疫性,(尤指通过注射疫苗)使免疫”,D项infect表示“感染,传染”。根据unless(除非)可知,后面的句子表示条件,结合前面的句子children cannot be enrolled in schools or day care(儿童不能上学或上托儿所)以及后面的tetanus(破伤风)、diphtheria(白喉)等词,可知“使免疫”符合语境。句意:美国许多州都通过了法律,规定儿童不能上学或上托儿所,除非他们已经接种了预防破伤风、白喉、麻疹、腮腺炎和百日咳的疫苗。因此,该题选择C项正确。