To see is to believe. 百聞不如一見，不定詞當主詞用，而本句To still be suffering是不定詞片詞用分詞，是強調用意，當主詞用
...out of the U.S. 3. Even being illegal, banks may still allow your friend to open an account.
Although (she is) unable to walk, Helen is still happy. ←← 本句的主因是主詞一致，(she is)才符合文法。 例1. ...
The system says it sent a verification code to my e-mail when I failed to log in, but I still haven’t received the verification code yet from my email.