He gave a lame excuse for being absent.

他找不住脚借口来解释缺席原因。

He tried to justify his absence with lame excuses.

他想用不住脚借口为自己缺席辩解。

I find your theory is untenable and it must be rejected.

我觉得你理论是不住脚, 必予以摒弃。

This disproves the theory that children are purely imitative.

这证明认为儿童只会单纯地模仿理论是不住脚。

I incline to the view that this conclusion is untenable.

我赞同该结论不住脚这一观点。

Only the most ingenuous person would believe such a weak excuse!

只有最天真会相信这么一不住脚借口!

This argument, however, does not hold water.

但是,这种观点是不住脚。

The argument won't wash.

那论点不住脚。