The flu is believed _______ by viruses that like to reproduce in the cells inside the human nose and throat.
It is thought that ___ is the leading factor contributing to language learning.
Mike broke the window, but I didn’t punish him for the reason that he didn’t do it _________.
you’d better ________ his telephone number , his name and address in your notebook before you forget them.
Judy and I are flying to London for a holiday and I will ________ the chance to practice my spoken English.
She expressed her thanks to the policeman sincerely, because he ______ the famous painting which had been stolen a year before.