I know that when the situation is unreal, we use the "if" clause plus past tense.
If you didn't know English, you would not know how to solve these problems.
[The fact is that the person knows English and probably knows how to do the problem]
My question is that: Will it be ok if I also use past tense to describe an unreal situation without using "if".
He is pretending he didn't know how to speak English.
He acts like he didn't know how to speak English.
[the fact is that he knows English]