it is difficult to do sth.正确吗？

你好, 正确的搭配是

It is difficult to do sth, 或 Doing sth

is difficult. To do sth is difficult.

都可以表示, 做某事很难。

还有个很常见的短语, have difficulty

in doing sth, 表示做某事有困难, 很难.

希采纳