when they heard the news, they started to cray
here we have to verbs
start & cry , so the second should be in the infinitive form
I agree that "crying" and "to cry" both work.
Crying (a gerund) or to cry (an infinitive) can both work as the object of the verb "Started". No one should argue because they are both correct. :)
after verbs BEGIN, START, STOP,...always put "verbING".
That is simply incorrect. You cannot have learned this from any grammar of English.