When Venus begins to cross the Sun's disc, it looks smeared not circular—which makes it difficult to establish timings.

当金星开始穿过太阳的圆盘时，它看起来有斑点，不是圆形的——这使得确定时间变得困难。

youdao

But it is also this natural tendency that makes trading (which looks like it should be easy) extremely difficult.

但是就是这个自然倾向导致交易(看起来很简单)极度困难。

youdao

He no longer has to fight an election which looks extremely difficult to win and leaves office with his political reputation at least partially salvaged.

BBC: Martha Kearney's week

And if you know much about filmmaking you know how difficult it is to make something like that look the way it looks in this, which is terribly disorganized and yet not have these guys hurt each other while they're doing it.

NPR: A Trip On The Pineapple Express