Where you last Monday?—I went to the library.

Some people are worrying about the possibility ________ mobile phones could be responsible for a range of illnesses, from rashes(皮疹) to brain tumors．

I like eggs _____ breakfast. [ ]

Is your father still in Shanghai? —Yes, he _________there for two weeks.

I only know we will have a League meeting, but I have no idea when _________ it．