fall back on (或upon)

• • 求助于，求…的支持，转而依靠：

    Doctors sometimes fall back on old cures.

    医生们有时求助于传统疗法。

  • 退守，撤退：

    The battle is going badly for us,we'd better fall back on the town in the hills.

    战斗对我们越来越不利，我们最好退守到山中的小镇。

  • 重提，回过来再谈，回到…上面来：

    I must fall back upon what I said previously.

    我必须言归正传。

  • 往后退倒在…上：

    The tired worker fell back on the bed and at once fell asleep.

    疲倦的工人倒在床上就马上睡着了。