Previously, it had been impracticable to try to measure lightning even if a mega flash occurred.

以前，即使发生超级闪电，也无法进测量。

The logic was appealing, but unfortunately no one knew how much salt was in the sea or by how much it increased each year, which rendered the experiment impracticable.

这个道理很吸引人，但幸的是，谁也知道海洋里究竟有少盐，也知道每年到底少，这就使得这项实验无法付诸实施。

The project was a bold one, full of difficulty, perhaps impracticable. Mr. Fogg was going to risk life, or at least liberty, and therefore the success of his tour.

这个救人的打算是很冒险的，是有困难的，看来也是的。

On the morrow of that Monday, Earnshaw being still unable to follow his ordinary employments, and therefore remaining about the house, I speedily found it would be impracticable to retain my charge beside me, as heretofore.

那个星期一之后，恩萧仍然能去作他的日常工作，因此就逗留在屋里，我很快地发觉要像以前那样担任照顾我身边的小姐之责，是的了。

In a short time, finding the task which I had undertaken impracticable, as the birds poured in in countless multitudes, I rose, and, counting the dots then put down, found that one hundred and sixty-three had been made in twenty-one minutes

一会儿，我便发现我的记录完全无济于事，鸽群铺天盖地断涌来，成片成队委实难计其数。我站立起来，数了数刚记下的标记，短短21分钟里，竟有163个鸽群在我眼前呼啸而过。