Most southern states had set up primary school systems by the late eighteenth century,but only in New England____and ope
问题描述：
Most southern states had set up primary school systems by the late eighteenth century,but only in New England____and open to all students.A.primary schools were free B.free were primary schools C.were free primary schools D.were primary schools free
答
选D.
句首有only,句子是部分倒装,故排除A、B.
又因为and后有open,故and前的词应与open并列.故选D.