[问答题]
The graph shows the typical immune )5 i qy;e7p6)xypk yqsresp* 2co2p mc) t op3d5pvw7cge9 ktl6j.monse to two doses of a vaccine.
1.State which type of molecule stimulates antibody production.
2.Distinguish between the primary and secondary responses.
3.Explain how vaccination leads to long-term immunity.
