A grammer question about passive voice and active voice
There is a sentence like this: The insect is too difficult to see without using the microscope.

Why it can't be like this: The insect is too difficult to be seen without using the microscope.

Thank you!

Question

A grammer question about passive voice and active voice
There is a sentence like this: The insect is too difficult to see without using the microscope.

Why it can't be like this: The insect is too difficult to be seen without using the microscope.

Thank you!

Answer

too difficult to see

to difficult to + verb ... has a passive voice meaning, but the verb is not in the passive voice.
Likewise: too easy to do; too hot to touch; to ugly to look at; etc

Answer

The active voice version of your sentence would be, "One can't see the insect [without difficulty] without a microscope."  Your second version is the correct passive form: we use the past participle form of the verb ("seen") in passives.  The first version almost sounds like the INSECT cannot see without difficulty unless it uses a microscope!

Answer

actively passive voice:

You will be chewed out by me. :P

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!