Fixed grammar ch15
Fixed grammar ch15

RossRogers/qmlbook,RossRogers/qmlbook,RossRogers/qmlbook,dk0104/qmlbook,RossRogers/qmlbook,GuillaumeBelz/qmlbook,manashmndl/qmlbook,dk0104/qmlbook,jmertz/qmlbook,dk0104/qmlbook,talalbutt/qmlbook,meizhoubao/qmlbook,manashmndl/qmlbook,meizhoubao/qmlbook,jmertz/qmlbook,manashmndl/qmlbook,GuillaumeBelz/qmlbook,meizhoubao/qmlbook,meizhoubao/qmlbook,GuillaumeBelz/qmlbook,manashmndl/qmlbook,talalbutt/qmlbook,RossRogers/qmlbook,jmertz/qmlbook,jmertz/qmlbook,GuillaumeBelz/qmlbook,talalbutt/qmlbook,meizhoubao/qmlbook,talalbutt/qmlbook,dk0104/qmlbook,jmertz/qmlbook,GuillaumeBelz/qmlbook,manashmndl/qmlbook,dk0104/qmlbook,talalbutt/qmlbook