1.AI组合
在重读音节中读[ei],
例如：e-mail [i:'meil] straight [streit] train [trein] afraid [ə'freid] wait [weit] rain [rein] painting ['peintiŋ] main [mein]complain [kəm'plein] pain [pein] fail [feil] mainland ['meinlənd] rail [reil] tail [teil] painful ['peinfəl];
AI组合在非重读音节中读[ə/i]
例如：certainly ['sə:tənli] mountain ['mauntin] Britain ['britən] captain ['kæptin];
