Do you think necessary to do a bird count ?Yes , we must count them at least once a year

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 think____ important to learn English well.

Mrs Green are very grateful to the neighbour _____ helped her child out of the fire．

“I am a singer” is one of _______ TV shows at present.