I must not be cast down.

我绝对不能被压倒。

A born optimist, he refused to be cast down.

作为一个天生的乐观主义者，他拒绝沮丧。

Anyone would be cast down by such news as that.

像那样的消息会使任何人感到沮丧。

Don' t let yourself be cast down by a small failure in the experiment ; try again.

别为了实验中的小小失败而垂头丧气；再试下去。――（说明）作此义解时常用被动语态。

In making scientific experiments, one should not be cast down by temporary setbacks.

进行科学实验时，不应因为暂时的挫折就垂头丧气。