Such tall towers are not easy to build.
Her ideas can be explained in this way.
Junk food is not healthy to eat.
Your advice is impossible to follow.
It's hard to leard Japanese.
It was difficult to believe the fact.
Изменение подлежащего с "it" на дополнение. Например, с "it" на "tall towers" в первом предложении, с "it" на "her ideas" во втором и т. д.
