If you can't swim, don't go out of your depth.

如果你不会游泳就别到水深没顶的地方去。

youdao

With the interactive mode (described below), this disk should not be required, but it's nice to have just in case you get out of your depth.

使用交互模式(后面将描述)则不需要这张磁盘，不过最好拥有一张以备急需时使用。

youdao

If you can get that level of depth of field for that cheap in order to single out your subjects in your photos, why not go for it?

如果你发现能花这么少的钱来取得这么浅的景深——足以把你的对象在相片中突出，为什么不马上配备一个呢。

youdao

Scorn or condescension will greet bluffers: if you're out of your depth, be honest your companion is probably an expert.

ECONOMIST: Business travel