6.They ralied _______our best .We mustn't let them down.（ ）A．us to do B.on us to do
问题描述：
6.They ralied _______our best .We mustn't let them down.（ ）A．us to do B.on us to do
答
是relied吧?
选B
rely on/upon sb/sth (to do sth)