While doing an exercise, I found that my grammar book says only verebing is correct after a be verb, such as
.. they found some things that make people more vulnerable to cating a cold. One negative influence is arguing. (not to argue)... another characteristis is being( not to be) a loner. ( from Top 20 Great grammar for great writier)
I am very confused because I was taught that I can use both to verb and verbing after a be verb, such as ..... is to argue......... is to be a loner. Am I wrong?